usb: gadget: f_hid: hidg_alloc() can be static

drivers/usb/gadget/function/f_hid.c:852:21: sparse: symbol 'hidg_alloc' was not declared. Should it be static?

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/function/f_hid.c

@@ -913,7 +913,7 @@ static void hidg_unbind(struct usb_configuration *c, struct usb_function *f)
 	usb_free_all_descriptors(f);
 }
 
-struct usb_function *hidg_alloc(struct usb_function_instance *fi)
+static struct usb_function *hidg_alloc(struct usb_function_instance *fi)
 {
 	struct f_hidg *hidg;
 	struct f_hid_opts *opts;