usb: gadget: composite: fix kernel-doc warnings

A few trivial fixes for composite driver:

Warning(include/linux/usb/composite.h:165): No description found for parameter
	'fs_descriptors'
Warning(include/linux/usb/composite.h:165): Excess struct/union/enum/typedef
	member 'descriptors' description in 'usb_function'
Warning(include/linux/usb/composite.h:321): No description found for parameter
	'gadget_driver'
Warning(drivers/usb/gadget/composite.c:1777): Excess function parameter 'bind'
	description in 'usb_composite_probe'

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Kosina <trivial@kernel.org>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/composite.c

@@ -1757,10 +1757,7 @@ static const struct usb_gadget_driver composite_driver_template = {
 /**
  * usb_composite_probe() - register a composite driver
  * @driver: the driver to register
- * @bind: the callback used to allocate resources that are shared across the
- *	whole device, such as string IDs, and add its configurations using
- *	@usb_add_config().  This may fail by returning a negative errno
- *	value; it should return zero on successful initialization.
+ *
  * Context: single threaded during gadget setup
  *
  * This function is used to register drivers using the composite driver

include/linux/usb/composite.h

@@ -60,7 +60,7 @@ struct usb_configuration;
  * @name: For diagnostics, identifies the function.
  * @strings: tables of strings, keyed by identifiers assigned during bind()
  *	and by language IDs provided in control requests
- * @descriptors: Table of full (or low) speed descriptors, using interface and
+ * @fs_descriptors: Table of full (or low) speed descriptors, using interface and
  *	string identifiers assigned during @bind().  If this pointer is null,
  *	the function will not be available at full speed (or at low speed).
  * @hs_descriptors: Table of high speed descriptors, using interface and
@@ -290,6 +290,7 @@ enum {
  *	after function notifications
  * @resume: Notifies configuration when the host restarts USB traffic,
  *	before function notifications
+ * @gadget_driver: Gadget driver controlling this driver
  *
  * Devices default to reporting self powered operation.  Devices which rely
  * on bus powered operation should report this in their @bind method.