drm/amdgpu:use hw_init for sriov_gpu_reset

no suspend invoked so after VF FLR by host, we just
call hw_init to reinitialize IPs.

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>