drm/amdgpu: move gpu reset out of amdgpu_device_suspend

Move it into the caller.  There are cases were we don't
want it.  We need it for hibernation, but we don't need
it for runtime pm, so drop it for runtime pm.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>