drm/amdgpu: add support for inplace IB patching for MM engines v2

We are going to need that for the second UVD instance on Vega20.

v2: rename to patch_cs_in_place

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-and-tested-by: James Zhu <James.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>