usb: gadget: libcomposite: move MODULE_VERSION to composite.c

MODULE_VERSION and AUTHOR looks better in composite.c than in
usbstrings.c so I move it there.
I put David Brownell as the module Author as I belive he wrote most of
it.

Acked-by: Michal Nazarewicz <[e-mail]>
Signed-off-by: Sebastian Andrzej Siewior <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/composite.c

···
 	}
 }
 EXPORT_SYMBOL_GPL(usb_composite_overwrite_options);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Brownell");

drivers/usb/gadget/usbstring.c

···
 	return buf [0];
 }
 EXPORT_SYMBOL_GPL(usb_gadget_get_string);
-MODULE_LICENSE("GPL");