xilinx: Add support for ENV_VARS_UBOOT_RUNTIME_CONFIG

Start to use ENV_VARS_UBOOT_RUNTIME_CONFIG to enable/disable updating
variables with run time information.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a3930b5..9b8dadc 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1085,6 +1085,7 @@
 	select DM_SERIAL
 	select OF_CONTROL
 	imply BOARD_LATE_INIT
+	imply ENV_VARS_UBOOT_RUNTIME_CONFIG
 
 config ARCH_VF610
 	bool "Freescale Vybrid"
@@ -1120,6 +1121,7 @@
 	imply CMD_CLK
 	imply CMD_DM
 	imply CMD_SPL
+	imply ENV_VARS_UBOOT_RUNTIME_CONFIG
 	imply FAT_WRITE
 
 config ARCH_ZYNQMP_R5
@@ -1159,6 +1161,7 @@
 	select ZYNQMP_IPI
 	imply BOARD_LATE_INIT
 	imply CMD_DM
+	imply ENV_VARS_UBOOT_RUNTIME_CONFIG
 	imply FAT_WRITE
 	imply MP
 	imply DM_USB_GADGET