arm64: rsi: Map unprotected MMIO as decrypted

arm64: rsi: Map unprotected MMIO as decrypted

Instead of marking every MMIO as shared, check if the given region is
"Protected" and apply the permissions accordingly.

Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20241017131434.40935-6-steven.price@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>