With the change in the modeset sequence this shouldn't be required
any more since the ->mode_set callback now gets called when the dvo
port is fully up and running.

Also limit the retry loop to 10 tries to avoid hanging the machine
while holding important modeset locks.

Cc: Thomas Richter <thor@math.tu-berlin.de>
Tested-by: Thomas Richter <thor@math.tu-berlin.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>