[media] omap_vout: avoid sleep_on race

sleep_on and its variants are broken and going away soon. This changes
the omap vout driver to use wait_event_interruptible_timeout instead,
which fixes potential race where the dma is complete before we
schedule.

[hans.verkuil@cisco.com: replaced interruptible_sleep_on_timeout by
wait_event_interruptible_timeout in the commit msg, obvious typo]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Mauro Carvalho Chehab <m.chehab@samsung.com>
Cc: linux-media@vger.kernel.org
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>