configs/imx6qsabresd: Add ext4 rootfs option

Allow building a ext4 rootfs type.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

configs/freescale_imx6qsabresd_defconfig

@@ -23,6 +23,7 @@ BR2_LINUX_KERNEL_INTREE_DTS_NAME="imx6q-sabresd"
 # filesystem
 BR2_ROOTFS_POST_IMAGE_SCRIPT="board/freescale/common/post-image.sh"
 BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
 
 # required tools to create the microSD image
 BR2_PACKAGE_HOST_DOSFSTOOLS=y