arm64: mte: Bitfield definitions for Asymm MTE

Add Asymmetric Memory Tagging Extension bitfield definitions.

Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20211006154751.4463-3-vincenzo.frascino@arm.com


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