arm64/neon: Add workaround for ambiguous C99 stdint.h types.

In a way similar to ARM commit 09096f6a ("ARM: 7822/1: add workaround
for ambiguous C99 stdint.h types"), this patch redefines the macros that
are used in stdint.h so its definitions of uint64_t and int64_t are
compatible with those of the kernel.

This patch comes from: https://patchwork.kernel.org/patch/3540001/


Wrote by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

We mark this file as a private file and don't have to override asm/types.h

Change-Id: I92b3ccc37817a888dd57c12da8f0ded8911f4441
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>