gsp-phys: mdev-owned backend lifecycle (P1)

Add the gsp_phys_mdev_owned ownership selector (default 0: unchanged
load-time module-owned claim/boot). With 1, module load claims nothing;
the first mdev create starts a refcounted backend session whose
claim+boot runs asynchronously from a work item, so mdev create and
init_work never block. The last mdev remove releases after the emulation
thread is stopped. Failures are fail-open: the backend stays OFF and the
mdev keeps serving the emulation path.

nv_vgpu_exit now gates the session STOPPING under the session lock,
drains the emulation threads via mdev_unregister_driver(), and only then
releases the claim; the module-owned path keeps its previous release
position. A start while STOPPING is refused and a concurrent second
stopper cannot release twice. No forwarding is added.

0 files changed, 0 insertions, 0 deletions