ti_omap4_common: use ext4 fs as default.

All TI SoCs expect filesystem to be ext4, omap4_common is the only one
with ext3. move omap4 to ext4 so that we can start consolidating MMC
arguments.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

include/configs/ti_omap4_common.h

@@ -92,7 +92,7 @@
 	"vram=16M\0" \
 	"mmcdev=0\0" \
 	"mmcroot=/dev/mmcblk0p2 rw\0" \
-	"mmcrootfstype=ext3 rootwait\0" \
+	"mmcrootfstype=ext4 rootwait\0" \
 	"mmcargs=setenv bootargs console=${console} " \
 		"vram=${vram} " \
 		"root=${mmcroot} " \