media: tvp5150: trigger autodetection on subdev open to reset cropping

If cropping isn't set explicitly by userspace, reset it to the maximum
possible rectangle in subdevice open if a standard change is detected.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
[m.felsch@pengutronix.de: move code from internal_ops.open() to pad_ops.init_cfg()]
[m.felsch@pengutronix.de: make use of tvp5150_set_default() helper]
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>