USB: ulpi: fix compilation warning

Fixes below compilation warning from ulpi.h

include/linux/usb/ulpi.h:145:
        warning: 'struct otg_io_access_ops' declared inside parameter list
include/linux/usb/ulpi.h:145:
         warning: its scope is only this definition or declaration,
         which is probably not what you want
Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/usb/ulpi.h

@@ -11,6 +11,7 @@
 #ifndef __LINUX_USB_ULPI_H
 #define __LINUX_USB_ULPI_H
 
+#include <linux/usb/otg.h>
 /*-------------------------------------------------------------------------*/
 
 /*