media: v4l2-ctrls: document nested members of structs

There are a few nested members at v4l2-ctrls.h. Now that
kernel-doc supports, document them.
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

include/media/v4l2-ctrls.h

@@ -166,8 +166,15 @@ typedef void (*v4l2_ctrl_notify_fnc)(struct v4l2_ctrl *ctrl, void *priv);
  *		empty strings ("") correspond to non-existing menu items (this
  *		is in addition to the menu_skip_mask above). The last entry
  *		must be NULL.
+ *		Used only if the @type is %V4L2_CTRL_TYPE_MENU.
+ * @qmenu_int:	A 64-bit integer array for with integer menu items.
+ *		The size of array must be equal to the menu size, e. g.:
+ *		:math:`ceil(\frac{maximum - minimum}{step}) + 1`.
+ *		Used only if the @type is %V4L2_CTRL_TYPE_INTEGER_MENU.
  * @flags:	The control's flags.
- * @cur:	The control's current value.
+ * @cur:	Structure to store the current value.
+ * @cur.val:	The control's current value, if the @type is represented via
+ *		a u32 integer (see &enum v4l2_ctrl_type).
  * @val:	The control's new s32 value.
  * @priv:	The control's private pointer. For use by the driver. It is
  *		untouched by the control framework. Note that this pointer is