arm64: include EXT4 in defconfig

Most readily available root filesystems are formatted as EXT4 these
days. For example, see the raring rootfs that the Debian folk is
preparing [1].

[1]: http://people.debian.org/~wookey/bootstrap/rootfs/

Cc: Will Deacon <will.deacon@arm.com>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/configs/defconfig

@@ -72,6 +72,7 @@ CONFIG_LOGO=y
 # CONFIG_IOMMU_SUPPORT is not set
 CONFIG_EXT2_FS=y
 CONFIG_EXT3_FS=y
+CONFIG_EXT4_FS=y
 # CONFIG_EXT3_DEFAULTS_TO_ORDERED is not set
 # CONFIG_EXT3_FS_XATTR is not set
 CONFIG_FUSE_FS=y