aarch64: Give up with MTE for AArch32 guest

KVM doesn't support combination of MTE and AArch32 guest, so do not
even try.

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20220520123844.127733-1-vladimir.murzin@arm.com


Signed-off-by: Will Deacon <will@kernel.org>