drm/amdgpu: Introduce reset domain

Defined a reset_domain struct such that
all the entities that go through reset
together will be serialized one against
another. Do it for both single device and
XGMI hive cases.

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Suggested-by: Christian König <ckoenig.leichtzumerken@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://www.spinics.net/lists/amd-gfx/msg74111.html