usb: gadget: remove unnecessary 'driver' argument

now that no UDC driver relies on the extra
'driver' argument to ->udc_stop(), we can
safely remove it.

This commit is based on previous work by
Robert Baldyga <r.baldyga@samsung.com> which
can be found at [1]; however that patch turned
out to have a high probability of regressing
many UDC drivers because of a blind search & replace
s/driver/$udc->driver/ which caused the 'driver'
argument to stop_activity() to be a valid non-NULL
pointer when it should be NULL, thus causing UDCs
to mistakenly call gadget driver's ->disconnect()
callback.

[1] http://markmail.org/message/x5zneg4xea4zntab

Acked-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/udc/goku_udc.c b/drivers/usb/gadget/udc/goku_udc.c
index bf9c5ef..5b9176e 100644
--- a/drivers/usb/gadget/udc/goku_udc.c
+++ b/drivers/usb/gadget/udc/goku_udc.c
@@ -992,8 +992,7 @@
 
 static int goku_udc_start(struct usb_gadget *g,
 		struct usb_gadget_driver *driver);
-static int goku_udc_stop(struct usb_gadget *g,
-		struct usb_gadget_driver *driver);
+static int goku_udc_stop(struct usb_gadget *g);
 
 static const struct usb_gadget_ops goku_ops = {
 	.get_frame	= goku_get_frame,
@@ -1364,8 +1363,7 @@
 		udc_enable(dev);
 }
 
-static int goku_udc_stop(struct usb_gadget *g,
-		struct usb_gadget_driver *driver)
+static int goku_udc_stop(struct usb_gadget *g)
 {
 	struct goku_udc	*dev = to_goku_udc(g);
 	unsigned long	flags;