arm64: dcache: select DCACHE_WORD_ACCESS for little-endian CPUs

DCACHE_WORD_ACCESS uses the word-at-a-time API for optimised string
comparisons in the vfs layer.

This patch implements support for load_unaligned_zeropad in much the
same way as has been done for ARM, although big-endian systems are also
supported.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: 7bc13fd33adb9536bd73965cd46bbf7377df097c
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


[imaund@codeaurora.org: Resolve merge conflicts]
Signed-off-by: Ian Maund <imaund@codeaurora.org>