media: atomisp: Add atomisp_pipe_check() helper

Several of the ioctl handlers all do the same checks
(isp->fatal_error and asd->streaming errors) add
an atomisp_pipe_check() helper for this.

Note this changes the vidioc_s_fmt_vid_cap and vidioc_s_input handlers
to now reject calls made while asd->streaming==STOPPING. This fixes
a possible race where one thread can make this ioctls while
vidioc_streamoff is running from another thread and it has
temporarily released isp->mutex to kill the watchdog timers / work.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>