ANDROID: drivers/arm-smmu-v3-kvm: Support IOMMU_DOMAIN_IDENTITY

Since all the hyp bits are there, we can use IOMMU_DOMAIN_IDENTITY
with KVM_IOMMU_IDMAPPED_DOMAIN.

This can be discovered per device from device tree using flag
"iommu-idmapped"

Bug: 277989609
Bug: 278749606
Change-Id: Icf003b4c2789f6025be77db54a670a5d0888e603
Signed-off-by: Mostafa Saleh <smostafa@google.com>