When coming back from DPMS or turning on a display, make sure we have
the watermarks set up before turning on the display plane, otherwise we
may get underruns.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: NDirk Hohndel <hohndel@infradead.org>
Signed-off-by: NEric Anholt <eric@anholt.net>