drm/amdgpu: properly handle GC vs MM in amdgpu_vmid_mgr_init()

When kernel queues are disabled, all GC vmids are available
for the scheduler.  MM vmids are still managed by the driver
so make all 16 available.

Also fix gmc 10 vs 11 mix up in
commit 1f61fc28 ("drm/amdgpu/mes: make more vmids available when disable_kq=1")

v2: Properly handle pre-GC 10 hardware

Fixes: 1f61fc28 ("drm/amdgpu/mes: make more vmids available when disable_kq=1")
Cc: Arvind Yadav <Arvind.Yadav@amd.com>
Reviewed-by: Arvind Yadav <Arvind.Yadav@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>