arm64: Remove __flush_dcache_page()

This function is only used in __sync_icache_dcache(), so remove it and
call __flush_dcache_area() directly. The flush_icache_user_range()
function is not used in the arm64 kernel.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Will Deacon <will.deacon@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Git-commit: ebd88367de80f9509bd30a09342d0a19c925b23e
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


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