drm/amdkfd: Delete unnecessary register settings

Those register settings have been performed in amdgpu initialization
gfxhub_v1_0_setup_vmid_config() and mmhub_v1_0_setup_vmid_config().
So no need to do it again in kfd.

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