drm/amdgpu: Implement get_vmid_pasid_mapping for gfx11

Implement gmc_v11_0_get_vmid_pasid_mapping_info to fix
gmc_v11_0_flush_gpu_tlb_pasid logic. Change from gfx10 to use
IH_VMID_*_LUT registers for VMID -> PASID mapping.

Signed-off-by: Graham Sider <Graham.Sider@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>