sh/rsk7203: add missing include net.h

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

board/renesas/rsk7203/rsk7203.c

@@ -21,6 +21,7 @@
  */
 
 #include <common.h>
+#include <net.h>
 #include <netdev.h>
 #include <asm/io.h>
 #include <asm/processor.h>