ppc4xx: Move cpu/ppc4xx/vecnum.h into include path

This patch allows the use of 4xx interrupt vector number defines
in board specific code outside cpu/ppc4xx.

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd-electronics.com>
diff --git a/cpu/ppc4xx/usbdev.c b/cpu/ppc4xx/usbdev.c
index 5924a6c..d71ba77 100644
--- a/cpu/ppc4xx/usbdev.c
+++ b/cpu/ppc4xx/usbdev.c
@@ -7,7 +7,7 @@
 
 #include <usb.h>
 #include "usbdev.h"
-#include "vecnum.h"
+#include <asm/ppc4xx-intvec.h>
 
 #define USB_DT_DEVICE        0x01
 #define USB_DT_CONFIG        0x02