colibri_imx7: use preboot for fdtfile evaluation

Enable and set preboot var with fdtfile evaluation.
preboot will be checked and run immediately before starting the
CONFIG_BOOTDELAY countdown and/or running the auto-boot command resp.
entering interactive mode.

This provides possibility to use different boot cmds in interactive mode
without manual setting fdtfile value, as it it's already evaluated
before entering interactive mode.

Fixes: a62c60610f("colibri_imx7_emmc: add Colibri iMX7D 1GB (eMMC) module support")
Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
diff --git a/configs/colibri_imx7_defconfig b/configs/colibri_imx7_defconfig
index f33ca11..a13a4bc 100644
--- a/configs/colibri_imx7_defconfig
+++ b/configs/colibri_imx7_defconfig
@@ -12,6 +12,8 @@
 CONFIG_DEFAULT_DEVICE_TREE="imx7-colibri-rawnand"
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/toradex/colibri_imx7/imximage.cfg,MX7D"
+CONFIG_USE_PREBOOT=y
+CONFIG_PREBOOT="setenv fdtfile ${soc}-colibri-${fdt_board}.dtb "
 CONFIG_BOOTDELAY=1
 # CONFIG_USE_BOOTCOMMAND is not set
 # CONFIG_CONSOLE_MUX is not set
diff --git a/configs/colibri_imx7_emmc_defconfig b/configs/colibri_imx7_emmc_defconfig
index e4b0c99..c8b6ce7 100644
--- a/configs/colibri_imx7_emmc_defconfig
+++ b/configs/colibri_imx7_emmc_defconfig
@@ -14,6 +14,8 @@
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/toradex/colibri_imx7/imximage.cfg,MX7D"
+CONFIG_USE_PREBOOT=y
+CONFIG_PREBOOT="setenv fdtfile ${soc}-colibri-emmc-${fdt_board}.dtb"
 CONFIG_BOOTDELAY=1
 # CONFIG_USE_BOOTCOMMAND is not set
 # CONFIG_CONSOLE_MUX is not set
diff --git a/include/configs/colibri_imx7.h b/include/configs/colibri_imx7.h
index 8cc5a36..76088d5 100644
--- a/include/configs/colibri_imx7.h
+++ b/include/configs/colibri_imx7.h
@@ -118,13 +118,11 @@
 
 #if defined(CONFIG_TARGET_COLIBRI_IMX7_NAND)
 #define CONFIG_BOOTCOMMAND "run ubiboot ; echo ; echo ubiboot failed ; " \
-	"setenv fdtfile ${soc}-colibri-${fdt_board}.dtb && run distro_bootcmd;"
+	"run distro_bootcmd;"
 #define MODULE_EXTRA_ENV_SETTINGS \
 	"mtdparts=" CONFIG_MTDPARTS_DEFAULT "\0" \
 	UBI_BOOTCMD
 #elif defined(CONFIG_TARGET_COLIBRI_IMX7_EMMC)
-#define CONFIG_BOOTCOMMAND \
-	"setenv fdtfile ${soc}-colibri-emmc-${fdt_board}.dtb && run distro_bootcmd;"
 #define MODULE_EXTRA_ENV_SETTINGS \
 	"variant=-emmc\0" \
 	EMMC_ANDROID_BOOTCMD