media: cec-gpio: use GPIOD_OUT_HIGH_OPEN_DRAIN

This driver needs a pull up output GPIO, but devm_gpiod_get() is called
with GPIOD_IN. This apparently works fine for the RPi3 where the DT
correctly specifies a pull up GPIO, but on the i.MX6 it also needs to
be specified with devm_gpiod_get().

Reported-by: Henrik Mau <Henrik.Mau@linn.co.uk>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>