drm/xe: Take job list lock in xe_sched_first_pending_job

Access to the pending_list should always happens under job_list_lock.

Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241105160327.2970277-1-nirmoy.das@intel.com


Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>