kselftest/arm64: Add TPIDR2 to the set of known signal context records

When validating the set of signal context records check that any TPIDR2
record has the correct size, also suppressing warnings due to seeing an
unknown record type.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221208-arm64-tpidr2-sig-v3-3-c77c6c8775f4@kernel.org


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