media: microchip-isc: Remove dead code in pipeline validation

The isc_try_fse() function, called from isc_validate(), takes two
parameters, an isc_device pointer, and a v4l2_subdev_state pointer. The
isc_device is accessed but not modified by the function. The state is
modified, including the struct v4l2_subdev_pad_config array it points
to, but they are then never used by the caller. Furthermore, the V4L2
subdev operation called by isc_try_fse() doesn't modify the subdev it is
called on. The isc_try_fse() function has thus no effect, and can just
be dropped.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Eugen Hristev <eugen.hristev@collabora.com>
Tested-by: Eugen Hristev <eugen.hristev@collabora.com>
[Sakari Ailus: Resolve conflicts due to API changes.]
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>