drm/i915/debugfs: Update pageflip information

Show the last submitted seqno to the engine, not the overall next seqno,
as this is more pertinent information when inspecting the pageflip and
whether the CS or display engine stalled.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20161124144750.2610-2-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -549,10 +549,10 @@ static int i915_gem_pageflip_info(struct seq_file *m, void *data)
 			if (work->flip_queued_req) {
 				struct intel_engine_cs *engine = work->flip_queued_req->engine;
 
-				seq_printf(m, "Flip queued on %s at seqno %x, next seqno %x [current breadcrumb %x], completed? %d\n",
+				seq_printf(m, "Flip queued on %s at seqno %x, last submitted seqno %x [current breadcrumb %x], completed? %d\n",
 					   engine->name,
 					   work->flip_queued_req->global_seqno,
-					   atomic_read(&dev_priv->gt.global_timeline.seqno),
+					   intel_engine_last_submit(engine),
 					   intel_engine_get_seqno(engine),
 					   i915_gem_request_completed(work->flip_queued_req));
 			} else