arm64: realm: ioremap: Allow mapping memory as encrypted

For ioremap(), so far we only checked if it was a device (RIPAS_DEV) to choose
an encrypted vs decrypted mapping. However, we may have firmware reserved memory
regions exposed to the OS (e.g., EFI Coco Secret Securityfs, ACPI CCEL).
We need to make sure that anything that is RIPAS_RAM (i.e., Guest
protected memory with RMM guarantees) are also mapped as encrypted.

Rephrasing the above, anything that is not RIPAS_EMPTY is guaranteed to be
protected by the RMM. Thus we choose encrypted mapping for anything that is not
RIPAS_EMPTY. While at it, rename the helper function

  __arm64_is_protected_mmio => arm64_rsi_is_protected

to clearly indicate that this not an arm64 generic helper, but something to do
with Realms.

Cc: Sami Mujawar <sami.mujawar@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>