drm/sun4i: Report proper vblank

The sun4i display engine doesn't have any vblank counter. Use the proper
helper for that.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
This commit is contained in:
Maxime Ripard 2016-06-20 12:20:58 +02:00
commit 0b340405fc