drm/v3d: Disable preemption while updating GPU stats

We forgot to disable preemption around the write_seqcount_begin/end() pair
while updating GPU stats:

  [ ] WARNING: CPU: 2 PID: 12 at include/linux/seqlock.h:221 __seqprop_assert.isra.0+0x128/0x150 [v3d]
  [ ] Workqueue: v3d_bin drm_sched_run_job_work [gpu_sched]
 <...snip...>
  [ ] Call trace:
  [ ]  __seqprop_assert.isra.0+0x128/0x150 [v3d]
  [ ]  v3d_job_start_stats.isra.0+0x90/0x218 [v3d]
  [ ]  v3d_bin_job_run+0x23c/0x388 [v3d]
  [ ]  drm_sched_run_job_work+0x520/0x6d0 [gpu_sched]
  [ ]  process_one_work+0x62c/0xb48
  [ ]  worker_thread+0x468/0x5b0
  [ ]  kthread+0x1c4/0x1e0
  [ ]  ret_from_fork+0x10/0x20

Fix it.

Cc: Maíra Canal <mcanal@igalia.com>
Cc: stable@vger.kernel.org # v6.10+
Fixes: 6abe93b6 ("drm/v3d: Fix race-condition between sysfs/fdinfo and interrupt handler")
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Acked-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240813102505.80512-1-tursulin@igalia.com