media: ipu3-imgu: Fix NULL pointer dereference in active selection access

In the Linux kernel, the following vulnerability has been resolved:

media: ipu3-imgu: Fix NULL pointer dereference in active selection access

What the IMGU driver did was that it first acquired the pointers to active

and try V4L2 subdev state, and only then figured out which one to use.

The problem with that approach and a later patch (see Fixes: tag) is that

as sd_state argument to v4l2_subdev_get_try_crop() et al is NULL, there is

now an attempt to dereference that.

Fix this.

Also rewrap lines a little.