kernel-doc: Support arrays of pointers struct fields

In a rather unusual arrangement in include/media/v4l2-vp9.h struct
v4l2_vp9_frame_symbol_counts has fields that are arrays of pointers, not a
pointer to an array, which is what's usually done.

Add support for such arrays of pointers to kernel-doc.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240131084934.191226-1-sakari.ailus@linux.intel.com