drm/amdgpu: add a compute pipe reset for RS64

[Why]
Under SR-IOV, we are not sure whether pipe status is
good or not when doing initialization. The compute engine
maybe fail to bringup if pipe status is bad.

[How]
Do an RS64 pipe reset for MEC before we do initialization.
Also apply to bare-metal.

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Horace Chen <horace.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>