drm/amdgpu: group VM mapping tree with its lock (v2)

And also update the comment.

v2: agd: rebase on usptream.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
1 file changed