arm64: kconfig: allow CPU_BIG_ENDIAN to be selected

This patch wires up CONFIG_CPU_BIG_ENDIAN for the AArch64 kernel
configuration.

Selecting this option builds a big-endian kernel which can boot into a
big-endian userspace.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-commit: a872013d6d03ab63736a01dcd9747580be3a6b70
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


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