FROMGIT: arm64: mte: Conditionally compile mte_enable_kernel_*()

mte_enable_kernel_*() are not needed if KASAN_HW is disabled.

Add ash defines around the functions to conditionally compile the
functions.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210315132019.33202-7-vincenzo.frascino@arm.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Bug: 170327579
Bug: 172318110
(cherry picked from commit d8969752
 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/


 for-next/mte-async-kernel-mode)
Signed-off-by: Alexander Potapenko <glider@google.com>
Change-Id: If6ce3c28e970efda838b5f0112c409953265d083