drm/amdgpu/userq: integrate with enforce isolation

Enforce isolation serializes access to the GFX IP.  User
queues are isolated in the MES scheduler, but we still
need to serialize between kernel queues and user queues.
For enforce isolation, group KGD user queues with KFD user
queues.

v2: split out variable renaming, add config guards
v3: use new function names

Reviewed-by: Sunil Khatri <sunil.khatri@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>