gpu: host1x: Fix race in syncpt alloc/free

In the Linux kernel, the following vulnerability has been resolved: gpu: host1x: Fix race in syncpt alloc/free Fix race condition between host1x_syncpt_alloc() and host1x_syncpt_put() by using kref_put_mutex() instead of kref_put() + manual mutex locking. This ensures no thread can acquire the syncpt_mutex after the refcount drops to zero but before syncpt_release acquires it. This prevents races where syncpoints could be allocated while still being cleaned up from a previous release. Remove explicit mutex locking in syncpt_release as kref_put_mutex() handles this atomically.