modify ext4fs error problem

buildroot-external/configs/ark1668e_devb_emmc_defconfig

@@ -55,7 +55,7 @@ BR2_PACKAGE_ANDROID_TOOLS=y
 BR2_PACKAGE_UTIL_LINUX=y
 BR2_PACKAGE_UTIL_LINUX_LIBUUID=y
 BR2_TARGET_ROOTFS_EXT2=y
-BR2_TARGET_ROOTFS_EXT2_2r0=y
+BR2_TARGET_ROOTFS_EXT2_4=y
 BR2_TARGET_ROOTFS_EXT2_SIZE="500M"
 # BR2_TARGET_ROOTFS_TAR is not set
 BR2_LIBARKAPI_ARK1668E=y

u-boot/include/configs/ark1668e_devb_emmc.h

@@ -212,7 +212,7 @@
 		"root=${emmcroot} " \
 		"rootfstype=${emmcrootfstype}\0" \
 	"emmcroot=/dev/mmcblk0p10 rw\0" \
-	"emmcrootfstype=ext2 rootwait\0" \
+	"emmcrootfstype=ext4 rootwait\0" \
 	"emmcboot=echo Booting from emmc ...; " \
 		"run emmcargs; " \
 		"mmc dev ${emmc_dev_part}; " \