drm/amdgpu: Add XCC inst to PASID TLB flushing

Add XCC instance to select the correct KIQ ring when
flushing TLBs on a multi-XCC setup.

Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Tested-by: Amber Lin <Amber.Lin@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>