net: macb: fix build break with !CONFIG_OF

This fixes the build of the macb driver that was broken by the DT changes:

drivers/net/ethernet/cadence/macb.c:1503: error: implicit declaration of function 'of_match_ptr'
drivers/net/ethernet/cadence/macb.c:1503: error: 'macb_dt_ids' undeclared here (not in a function)
drivers/net/ethernet/cadence/macb.c:1503: error: initializer element is not constant
drivers/net/ethernet/cadence/macb.c:1503: error: (near initialization for 'macb_driver.driver.of_match_table')

Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

drivers/net/ethernet/cadence/macb.c

@@ -23,6 +23,7 @@
 #include <linux/platform_data/macb.h>
 #include <linux/platform_device.h>
 #include <linux/phy.h>
+#include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/of_net.h>