iommu/arm-smmu-v3: Make SVA allocate a normal arm_smmu_domain

iommu/arm-smmu-v3: Make SVA allocate a normal arm_smmu_domain

Currently the SVA domain is a naked struct iommu_domain, allocate a struct
arm_smmu_domain instead.

This is necessary to be able to use the struct arm_master_domain
mechanism.

Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Michael Shavit <mshavit@google.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/8-v9-5cd718286059+79186-smmuv3_newapi_p2b_jgg@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>