wl12xx: fix non-wl12xx build scenarios

Support building wl1271-equipped boards without building the
wl1271 driver itself, e.g.:

CONFIG_MACH_OMAP_ZOOM3=y
CONFIG_WL12XX is not set

Reported-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>

include/linux/wl12xx.h

@@ -32,7 +32,20 @@ struct wl12xx_platform_data {
 	int board_ref_clock;
 };
 
+#ifdef CONFIG_WL12XX_PLATFORM_DATA
+
 int wl12xx_set_platform_data(const struct wl12xx_platform_data *data);
+
+#else
+
+static inline
+int wl12xx_set_platform_data(const struct wl12xx_platform_data *data)
+{
+	return -ENOSYS;
+}
+
+#endif
+
 const struct wl12xx_platform_data *wl12xx_get_platform_data(void);
 
 #endif