arm64: cpufeature: add TCR2 cpucap

This capability indicates if the system supports the TCR2_ELx system register.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230606145859.697944-7-joey.gouly@arm.com


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