drm_sched_job_timedout works with drm_sched_stop as a pair,
so we'd better use the drm_sched_fault helper to make the
error and timeout handling go the same path.

This also fixes application hang when task error.
Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Tested-by: Andreas Baierl <ichgeh@imkreisrum.de>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200101103831.22429-1-yuq825@gmail.com