i.MX6: mx6qsabrelite: add ext2 support

Current Ubuntu releases from Freescale contain a boot script in ext3 filesystem.
Signed-off-by: NEric Nelson <eric.nelson@boundarydevices.com>

include/configs/mx6qsabrelite.h

@@ -64,6 +64,7 @@
 #define CONFIG_MMC
 #define CONFIG_CMD_MMC
 #define CONFIG_GENERIC_MMC
+#define CONFIG_CMD_EXT2
 #define CONFIG_CMD_FAT
 #define CONFIG_DOS_PARTITION