arm64/sysreg: Add definition for ICC_NMIAR1_EL1

FEAT_NMI adds a new interrupt status register for NMIs, ICC_NMIAR1_EL1.
Add the definition for this register as per IHI0069H.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221208-arm64-isr-el1-v2-1-89f7073a1ca9@kernel.org


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