imx: mx6slevk: introduce device tree support

Introduce device tree support.
dts from kernel commit c4f3f22edd Merge tag 'linux-kselftest-4.11-rc1'

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
diff --git a/configs/mx6slevk_spinor_defconfig b/configs/mx6slevk_spinor_defconfig
index e1c9118..e03e0a7 100644
--- a/configs/mx6slevk_spinor_defconfig
+++ b/configs/mx6slevk_spinor_defconfig
@@ -1,6 +1,7 @@
 CONFIG_ARM=y
 CONFIG_ARCH_MX6=y
 CONFIG_TARGET_MX6SLEVK=y
+CONFIG_DEFAULT_DEVICE_TREE="imx6sl-evk"
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/freescale/mx6slevk/imximage.cfg,MX6SL"
 CONFIG_SPI_BOOT=y
 CONFIG_BOOTDELAY=3
@@ -24,10 +25,10 @@
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
+CONFIG_OF_CONTROL=y
 CONFIG_DM=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_DM_THERMAL=y
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y
-CONFIG_OF_LIBFDT=y