usb: udc: add udc.h include file

Move common definitions to udc.h
This allows musb_udc.h to be removed as well.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
diff --git a/drivers/usb/musb/musb_udc.c b/drivers/usb/musb/musb_udc.c
index 3e3e05e..87640f4 100644
--- a/drivers/usb/musb/musb_udc.c
+++ b/drivers/usb/musb/musb_udc.c
@@ -39,7 +39,8 @@
  */
 
 #include <common.h>
-#include <usb/musb_udc.h>
+#include <usbdevice.h>
+#include <usb/udc.h>
 #include "../gadget/ep0.h"
 #include "musb_core.h"
 #if defined(CONFIG_USB_OMAP3)