USB: Add nop functions for !USB case

OTG drivers that use USB core functions like usb_add_hcd, usb_remove_hcd,
etc can be selected for gadget only mode without selecting CONFIG_USB.

Change-Id: Ie4b0c1703622cc9051ad9f50b8901f0005daeeb6
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index 0097136..b43a097 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -379,9 +379,18 @@
 extern struct usb_hcd *usb_get_hcd(struct usb_hcd *hcd);
 extern void usb_put_hcd(struct usb_hcd *hcd);
 extern int usb_hcd_is_primary_hcd(struct usb_hcd *hcd);
+#ifdef CONFIG_USB
 extern int usb_add_hcd(struct usb_hcd *hcd,
 		unsigned int irqnum, unsigned long irqflags);
 extern void usb_remove_hcd(struct usb_hcd *hcd);
+#else
+static inline int
+usb_add_hcd(struct usb_hcd *hcd, unsigned int irqnum, unsigned long irqflags)
+{
+	return 0;
+}
+static inline void usb_remove_hcd(struct usb_hcd *hcd) {}
+#endif
 
 struct platform_device;
 extern void usb_hcd_platform_shutdown(struct platform_device *dev);