ANDROID: KVM: arm64: Initialize pkvm_pgtable.mm_ops earlier

The `init` callback of an IOMMU driver is called just before
`finalize_host_mappings` so that EL2 mappings created by drivers are
subsequently unmapped from host stage-2. However, at this point hyp has
already switched to the buddy allocator, having reserved pages allocated
by the early allocator, but `pkvm_pgtable.mm_ops` have not been switched
to buddy allocator callbacks. As a result, pages allocated for EL2
mappings of the IOMMU driver are allocated by the obsoleted early
allocator and remain treated as free by the buddy allocator. This likely
leads to a corruption in the free page lists and a later hyp panic.

Move the initialization of `pkvm_pgtable.mm_ops` before
`finalize_host_mappings` and the call to IOMMU's `init`.

Test: run a VM
Test: adb shell cmd jobscheduler run -f android 5132250
Bug: 190463801
Bug: 209004831
Signed-off-by: David Brazdil <dbrazdil@google.com>
Change-Id: I42ad28e6b4cfb014d50dbbf722e4c02d5f684178