ANDROID: KVM: arm64: Add __pkvm_iommu_init HVC to initialize IOMMU driver

IOMMU drivers so far have been initialized by directly assigning EL2
variables before __pkvm_init. That's not possible for out-of-tree
drivers that can only be initialized from early modules running between
__pkvm_init and __pkvm_prot_finalize.

Add a new HVC that can only be called before __pkvm_prot_finalize to set
the EL2 variables that way.

Also add an argument for kvm_iommu_ops.init so as to allow passing
dynamic arguments (such as location of config struct) to the driver.

@smostafa
Merge with new IOMMU EL1 code
Apply new calls to SMMUv3 driver

This commit changes the init flow of KVM IOMMU driver and it might
differ between builtin and modules(not supported yet).

For a builtin driver:
- An early initcall as core_initcall would call
  kvm_iommu_register_driver which mainly registers a EL1 driver with
  KVM.

- When pKVM is still privileged and before it drops it, it calls
  the driver Init callback, which then probes the driver and
  call kvm_iommu_init_hyp.

- kvm_iommu_init_hyp would call the EL2 driver init, which expects
  the EL1 driver to be probed and IOMMU are existing in the driver
  specific shared structs.

We need the extra step for the callback because we need to know when
pKVM is ready to have the IOMMU hypercalls, and unlike EL2 modules
builtin driver are not loaded by KVM.

For modules in the module init it can both porbe and init the hyp HVC
and ignore the drop privilege callback.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Bug: 277989609
Bug: 278749606
Change-Id: Iba683e7a26f2944407587661dc3ab1b0d098bdc7