warp7: Use PARTUUID to specify the rootfs location

warp7 can run different kernel versions, such as NXP 4.1 or mainline.

Currently the rootfs location is passed via mmcblk number and the
problem with this approach is that the mmcblk number for the eMMC
changes depending on the kernel version.

In order to avoid such issue, use UUID method to specify the rootfs
location.

Succesfully tested booting a NXP 4.1 and also a mainline kernel.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>

include/configs/warp7.h

@@ -29,6 +29,9 @@
 #define CONFIG_SYS_FSL_ESDHC_HAS_DDR_MODE
 #define CONFIG_SYS_MMC_IMG_LOAD_PART	1
 
+#define CONFIG_PARTITION_UUIDS
+#define CONFIG_CMD_PART
+
 #define CONFIG_DFU_ENV_SETTINGS \
 	"dfu_alt_info=boot raw 0x2 0x400 mmcpart 1\0" \
 
@@ -45,9 +48,9 @@
 	"ip_dyn=yes\0" \
 	"mmcdev="__stringify(CONFIG_SYS_MMC_ENV_DEV)"\0" \
 	"mmcpart=" __stringify(CONFIG_SYS_MMC_IMG_LOAD_PART) "\0" \
-	"mmcroot=" CONFIG_MMCROOT " rootwait rw\0" \
+	"finduuid=part uuid mmc 0:2 uuid\0" \
 	"mmcargs=setenv bootargs console=${console},${baudrate} " \
-		"root=${mmcroot}\0" \
+		"root=PARTUUID=${uuid} rootwait rw\0" \
 	"loadbootscript=" \
 		"fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${script};\0" \
 	"bootscript=echo Running bootscript from mmc ...; " \
@@ -55,6 +58,7 @@
 	"loadimage=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${image}\0" \
 	"loadfdt=fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr} ${fdt_file}\0" \
 	"mmcboot=echo Booting from mmc ...; " \
+		"run finduuid; " \
 		"run mmcargs; " \
 		"if test ${boot_fdt} = yes || test ${boot_fdt} = try; then " \
 			"if run loadfdt; then " \
@@ -125,7 +129,6 @@
 
 #define CONFIG_SYS_MMC_ENV_DEV		0
 #define CONFIG_SYS_MMC_ENV_PART		0
-#define CONFIG_MMCROOT			"/dev/mmcblk2p2"
 
 /* USB Configs */
 #define CONFIG_USB_STORAGE