iommu/amd: Remove unused amd_iommu_domain_update()

iommu/amd: Remove unused amd_iommu_domain_update()

All the callers have been removed by the below commit, remove the
implementation and prototypes.

Fixes: 322d889ae7d3 ("iommu/amd: Remove amd_iommu_domain_update() from page table freeing")
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/1-v2-9776c53c2966+1c7-amd_paging_flags_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>