arm64: setup: name 'tcr2' register

arm64: setup: name 'tcr2' register

TCR2_EL1 introduced some additional controls besides TCR_EL1. Currently
only PIE is supported and enabled by writing TCR2_EL1 directly if PIE
detected.

Introduce a named register 'tcr2' just like 'tcr' we've already had.
It'll be initialized to 0 and updated if certain feature detected and
needs to be enabled. Touch the TCR2_EL1 registers at last with the
updated 'tcr2' value if FEAT_TCR2 supported by checking
ID_AA64MMFR3_EL1.TCRX. Then we can extend the support of other features
controlled by TCR2_EL1.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Link: https://lore.kernel.org/r/20241102104235.62560-3-yangyicong@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>