USB: gadget rndis: send notifications

It turns out that atomic_inc_return() returns the *new* value
not the original one, so the logic in rndis_response_available()
kept the first RNDIS response notification from getting out.
This prevented interoperation with MS-Windows (but not Linux).

Fix this to make RNDIS behave again.
Signed-off-by: NRichard Röjfors <richard.rojfors@endian.se>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Cc: stable <stable@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/f_rndis.c

@@ -302,7 +302,7 @@ static void rndis_response_available(void *_rndis)
 	__le32				*data = req->buf;
 	int				status;
 
-	if (atomic_inc_return(&rndis->notify_count))
+	if (atomic_inc_return(&rndis->notify_count) != 1)
 		return;
 
 	/* Send RNDIS RESPONSE_AVAILABLE notification; a