imx8mn: configs: add support for distro boot commands

Supported boot device types in iMX8MN: MMC, DHCP.

Add DISTRO_DEFAULTS config option and include the distro boot command
header file to enable full support of distro boot on i.MX8M Nano EVK (both
DDR and LPDDR derivatives).

Drop previous environment, which was targeting customized boot commands and
boot order.

Signed-off-by: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
Cc: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
diff --git a/configs/imx8mn_ddr4_evk_defconfig b/configs/imx8mn_ddr4_evk_defconfig
index a3e51ba..8eca79f 100644
--- a/configs/imx8mn_ddr4_evk_defconfig
+++ b/configs/imx8mn_ddr4_evk_defconfig
@@ -19,6 +19,7 @@
 CONFIG_SPL=y
 CONFIG_SPL_IMX_ROMAPI_LOADADDR=0x48000000
 CONFIG_DEFAULT_DEVICE_TREE="imx8mn-ddr4-evk"
+CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT=y
 CONFIG_FIT_EXTERNAL_OFFSET=0x3000
 CONFIG_SPL_LOAD_FIT=y
diff --git a/configs/imx8mn_evk_defconfig b/configs/imx8mn_evk_defconfig
index 86601eb..e477028 100644
--- a/configs/imx8mn_evk_defconfig
+++ b/configs/imx8mn_evk_defconfig
@@ -20,6 +20,7 @@
 CONFIG_SPL=y
 CONFIG_SPL_IMX_ROMAPI_LOADADDR=0x48000000
 CONFIG_DEFAULT_DEVICE_TREE="imx8mn-evk"
+CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT=y
 CONFIG_FIT_EXTERNAL_OFFSET=0x3000
 CONFIG_SPL_LOAD_FIT=y
diff --git a/include/configs/imx8mn_evk.h b/include/configs/imx8mn_evk.h
index 596e255..985bec8 100644
--- a/include/configs/imx8mn_evk.h
+++ b/include/configs/imx8mn_evk.h
@@ -31,69 +31,29 @@
 
 #endif
 
+#ifndef CONFIG_SPL_BUILD
+#define BOOT_TARGET_DEVICES(func) \
+	func(MMC, mmc, 1) \
+	func(MMC, mmc, 2) \
+	func(DHCP, dhcp, na)
+
+#include <config_distro_bootcmd.h>
+#endif
+
 /* Initial environment variables */
 #define CONFIG_EXTRA_ENV_SETTINGS		\
-	"script=boot.scr\0" \
 	"image=Image\0" \
+	BOOTENV \
+	"scriptaddr=" __stringify(CONFIG_LOADADDR) "\0" \
+	"kernel_addr_r=" __stringify(CONFIG_LOADADDR) "\0" \
 	"console=ttymxc1,115200\0" \
-	"fdt_addr=0x43000000\0"			\
+	"fdt_addr_r=0x43000000\0"			\
 	"boot_fit=no\0" \
-	"fdt_file=" CONFIG_DEFAULT_FDT_FILE "\0" \
+	"fdtfile=" CONFIG_DEFAULT_FDT_FILE "\0" \
 	"initrd_addr=0x43800000\0"		\
 	"bootm_size=0x10000000\0" \
-	"mmcdev="__stringify(CONFIG_SYS_MMC_ENV_DEV)"\0" \
 	"mmcpart=" __stringify(CONFIG_SYS_MMC_IMG_LOAD_PART) "\0" \
 	"mmcroot=" CONFIG_MMCROOT " rootwait rw\0" \
-	"mmcautodetect=yes\0" \
-	"mmcargs=setenv bootargs console=${console} root=${mmcroot}\0 " \
-	"loadbootscript=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${script};\0" \
-	"bootscript=echo Running bootscript from mmc ...; " \
-		"source\0" \
-	"loadimage=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${image}\0" \
-	"loadfdt=fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file}\0" \
-	"mmcboot=echo Booting from mmc ...; " \
-		"run mmcargs; " \
-		"if test ${boot_fit} = yes || test ${boot_fit} = try; then " \
-			"bootm ${loadaddr}; " \
-		"else " \
-			"if run loadfdt; then " \
-				"booti ${loadaddr} - ${fdt_addr}; " \
-			"else " \
-				"echo WARN: Cannot load the DT; " \
-			"fi; " \
-		"fi;\0" \
-	"netargs=setenv bootargs console=${console} " \
-		"root=/dev/nfs " \
-		"ip=dhcp nfsroot=${serverip}:${nfsroot},v3,tcp\0" \
-	"netboot=echo Booting from net ...; " \
-		"run netargs;  " \
-		"if test ${ip_dyn} = yes; then " \
-			"setenv get_cmd dhcp; " \
-		"else " \
-			"setenv get_cmd tftp; " \
-		"fi; " \
-		"${get_cmd} ${loadaddr} ${image}; " \
-		"if test ${boot_fit} = yes || test ${boot_fit} = try; then " \
-			"bootm ${loadaddr}; " \
-		"else " \
-			"if ${get_cmd} ${fdt_addr} ${fdt_file}; then " \
-				"booti ${loadaddr} - ${fdt_addr}; " \
-			"else " \
-				"echo WARN: Cannot load the DT; " \
-			"fi; " \
-		"fi;\0"
-
-#define CONFIG_BOOTCOMMAND \
-	   "mmc dev ${mmcdev}; if mmc rescan; then " \
-		   "if run loadbootscript; then " \
-			   "run bootscript; " \
-		   "else " \
-			   "if run loadimage; then " \
-				   "run mmcboot; " \
-			   "else run netboot; " \
-			   "fi; " \
-		   "fi; " \
-	   "fi;"
 
 /* Link Definitions */
 #define CONFIG_LOADADDR			0x40480000