drm/amdgpu: add lock in kfd_process_dequeue_from_device

We need to take the reset domain lock before talking to MES. While in
this case we can take the lock inside the mes helper. We can't do so for
most other mes helpers since they are used during reset. So for
consistency sake we add the lock here.

Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>