microblaze: ml401 - add ifdef for GPIO

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/include/configs/ml401.h b/include/configs/ml401.h
index 1a2cb0a..b167cb2 100644
--- a/include/configs/ml401.h
+++ b/include/configs/ml401.h
@@ -64,8 +64,10 @@
 #undef ET_DEBUG
 
 /* gpio */
+#ifdef XILINX_GPIO_BASEADDR
 #define	CFG_GPIO_0		1
 #define	CFG_GPIO_0_ADDR		XILINX_GPIO_BASEADDR
+#endif
 
 /* interrupt controller */
 #define	CFG_INTC_0		1