hw/i386/amd_iommu: Rename amdviPCI TypeInfo

Per 'QEMU Coding Style':

  Naming
  ======
  Variables are lower_case_with_underscores; easy to type and read.

Rename amdviPCI variable as amdvi_pci.

amdviPCI_register_types() register more than PCI types:
TYPE_AMD_IOMMU_DEVICE inherits TYPE_X86_IOMMU_DEVICE which
itself inherits TYPE_SYS_BUS_DEVICE.

Rename it more generically as amdvi_register_types().

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210926175648.1649075-2-f4bug@amsat.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>