drm/amdgpu: add amdgpu soft reset

Check gpu status first, if MC/VMC/DISPLAY hang, directly triger full reset.
If engine hangs, then triger engine soft reset, if soft reset fails, will
fallback to full reset.

Signed-off-by: Chunming Zhou <David1.Zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>