usb: gadget: nokia: fix error recovery path for optional functions

In the nokia gadget some USB functions (obex 1 and 2, phonet) are optional.

If at the start of nokia_bind_config e.g. fi_phonet is an error pointer,
which can happen because we don't fail the bind process if
usb_get_function_instance() fails for fi_phonet, then f_phonet is NULL, and

phonet_stat = usb_add_function(c, f_phonet);

is never called and phonet_stat remains 0.

If, in these circumstances, we hit the err_conf label then !phonet_stat
evaluates to true and we try usb_remove_function() with its second
parameter being f_phonet which is NULL and it causes NULL pointer
dereference.

This patch changes the initial values of (obex1|obex2|phonet)_stat to a
nonzero value so that if the err_conf label is hit while the respective
functions have not been acquired the usb_remove_function() is not called
for those functions.
Signed-off-by: NAndrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>

drivers/usb/gadget/nokia.c

@@ -126,9 +126,9 @@ static int __init nokia_bind_config(struct usb_configuration *c)
 	struct usb_function *f_ecm;
 	struct usb_function *f_obex2 = NULL;
 	int status = 0;
-	int obex1_stat = 0;
-	int obex2_stat = 0;
-	int phonet_stat = 0;
+	int obex1_stat = -1;
+	int obex2_stat = -1;
+	int phonet_stat = -1;
 
 	if (!IS_ERR(fi_phonet)) {
 		f_phonet = usb_get_function(fi_phonet);