ANDROID: KVM: arm64: iommu: Use unified allocator interface

Instead of using shared memcache that requires ATOMIC allocation, use
a new iommu allocator.

For passing pages we use the new HVCs for unified allocator where pages
would be saved in the buddy allocator, this also adds a new feature
that allows the IOMMU code to allocate large order pages which was not
possible this can be used to allocate PGD for the SMMU.

Bug: 277989609
Bug: 278749606
Change-Id: I15a00d452a706211941107828870ca0d264c08de
Signed-off-by: Mostafa Saleh <smostafa@google.com>