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>
Git-commit: ade37198937a52bc3f59c40ffb14cb6688b273b7
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Ian Maund <imaund@codeaurora.org>