drivers: clean-up prom.h implicit includes

Powerpc is a mess of implicit includes by prom.h. Add the necessary
explicit includes to drivers in preparation of prom.h cleanup.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Grant Likely <grant.likely@linaro.org>

drivers/net/ethernet/freescale/xgmac_mdio.c

@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/phy.h>
 #include <linux/mdio.h>
+#include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/of_mdio.h>