drm/xe: cancel pending job timer before freeing scheduler

The async call to __guc_exec_queue_fini_async frees the scheduler
while a submission may time out and restart. To prevent this race
condition, the pending job timer should be canceled before freeing
the scheduler.

V3(MattB):
 - Adjust position of cancel pending job
 - Remove gitlab issue# from commit message
V2(MattB):
 - Cancel pending jobs before scheduler finish

Fixes: a20c75db ("drm/xe: Call __guc_exec_queue_fini_async direct for KERNEL exec_queues")
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250225045754.600905-1-tejas.upadhyay@intel.com


Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
(cherry picked from commit 18fbd567)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>