drm/amdkfd: Remove unnecessary register setting when invalidating tlb in kfd

Those register settings have been done in gfxhub_v1_0_program_invalidation()
and mmhub_v1_0_program_invalidation().

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