arm64: cpufeature: add Permission Overlay Extension cpucap

This indicates if the system supports POE. This is a CPUCAP_BOOT_CPU_FEATURE
as the boot CPU will enable POE if it has it, so secondary CPUs must also
have this feature.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20240822151113.1479789-6-joey.gouly@arm.com


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