pico-imx7d: Fix common distro configuration behavior

This sets DISTRO_CONFIG and BOOTCOMMAND, as well as add a `finduuid`
environment helper to allow it to properly work with Yocto Project and
other distributions using extlinux autogenerated configuration files.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>

configs/pico-imx7d_defconfig

@@ -3,26 +3,23 @@ CONFIG_ARCH_MX7=y
 CONFIG_SYS_TEXT_BASE=0x87800000
 CONFIG_TARGET_PICO_IMX7D=y
 CONFIG_IMX_RDC=y
+CONFIG_DISTRO_DEFAULTS=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/technexion/pico-imx7d/imximage.cfg"
-CONFIG_HUSH_PARSER=y
+CONFIG_BOOTCOMMAND="run finduuid; run distro_bootcmd"
 # CONFIG_CMD_BOOTD is not set
-CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_IMI is not set
 # CONFIG_CMD_XIMG is not set
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
-CONFIG_CMD_PART=y
 CONFIG_CMD_USB=y
 CONFIG_CMD_USB_MASS_STORAGE=y
 # CONFIG_CMD_SETEXPR is not set
-CONFIG_CMD_DHCP=y
+# CONFIG_CMD_MII is not set
 CONFIG_CMD_CACHE=y
-CONFIG_CMD_EXT2=y
-CONFIG_CMD_EXT4=y
 CONFIG_CMD_EXT4_WRITE=y
-CONFIG_CMD_FAT=y
-CONFIG_CMD_FS_GENERIC=y
+# CONFIG_ISO_PARTITION is not set
+# CONFIG_EFI_PARTITION is not set
 CONFIG_FSL_ESDHC=y
 CONFIG_PHYLIB=y
 CONFIG_USB=y

include/configs/pico-imx7d.h

@@ -49,6 +49,7 @@
 	"ramdisk_addr_r=0x83000000\0" \
 	"ramdiskaddr=0x83000000\0" \
 	"scriptaddr=" __stringify(CONFIG_LOADADDR) "\0" \
+	"finduuid=part uuid mmc 0:1 uuid\0" \
 	BOOTENV
 
 #define BOOT_TARGET_DEVICES(func) \