drm/amdgpu/gfx10: add ring reset callbacks

Add ring reset callbacks for gfx and compute.

v2: fix gfx handling
v3: wait for KIQ to complete

Acked-by: Vitaly Prosyak <vitaly.prosyak@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>