sema-svc: never consume a CE entry whose release was not delivered

The fake-release fallback acknowledged unreadable CE pushes even when the
tracking-semaphore pool page had no translation yet, so the GPFIFO entry was
consumed without writing the semaphore the client waits on (observed: client
stuck in UVM_GPU_REGISTER while CE channel 2's release never landed, its
push-buffer pin arriving ~2 s later).

- svc_fake_release now reports failure when the pool page cannot be
  translated/read/written instead of pretending success.
- CE channels with the fallback enabled leave the entry pending (no
  multi-second RAM rescue) until the pool pin lands; the skip path only
  consumes an entry when the release was actually delivered.

0 files changed, 0 insertions, 0 deletions