ANDROID: iommu/arm-smmu-v3-kvm: Implement reserved regions callback

Implement get_resv_regions of pKVM SMMUv3 callback. Since this does not
need to go into EL2, we can use the same function as non-pKVM. So Move
arm_smmu_get_resv_regions to common file shared with KVM.

Bug: 277989609
Bug: 339336590
Change-Id: I3456c13d4f009f83dd6c06ccf1cf47880b7027d3
Signed-off-by: Ryan Huang <tzukui@google.com>