drm/lima: add trace point for tasks

track lima task start which can be combined with
dma_fence_signal to identify task execution time.

example command to record:

trace-cmd record -i \
  -e "lima:lima_task_submit" -e "lima:lima_task_run" \
  -e "*fence:*fence_signaled" -e "drm:drm_vblank_event" \
  -e "drm:drm_vblank_event_queued" sleep 4

Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200307135438.9981-1-yuq825@gmail.com

drivers/gpu/drm/lima/lima_sched.h

@@ -6,6 +6,7 @@
 
 #include <drm/gpu_scheduler.h>
 #include <linux/list.h>
+#include <linux/xarray.h>
 
 struct lima_vm;