ARM: highbank: fix warning for calxedaxgmac_initialize

Add include of netdev.h to pick-up declaration of calxedaxgmac_initialize.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>

board/highbank/highbank.c

@@ -17,6 +17,7 @@
 
 #include <common.h>
 #include <ahci.h>
+#include <netdev.h>
 #include <scsi.h>
 
 #include <asm/sizes.h>