media: atmel: atmel-isi: initialize the try_crop for the pads in try_fmt

When requesting format from sensor, some sensors call the
subdev_get_try_crop which for ISI was not properly initialized, and this
causes errors in determining proper image resolutions.
To accommodate for this, when trying a format (in try_fmt), first attempt
to obtain the framesize for this format from sensor.
In case this fails, use the maximum ISI width/height as try_crop, otherwise
provide the first size height/width from the sensor.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>