arm64: Kill detection of VPIPT i-cache policy

Since the kernel will never run on a system with the VPIPT i-cache
policy, drop the detection code altogether.

Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20231204143606.1806432-3-maz@kernel.org


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