wl12xx: add platform data passing support

Add a simple mechanism to pass platform data to the
SDIO instances of wl12xx.

This way there is no confusion over who owns the 'embedded data',
typechecking is preserved, and no possibility for the wrong driver to
pick up the data.

Originally proposed by Russell King.

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/wl12xx/Kconfig b/drivers/net/wireless/wl12xx/Kconfig
index 2f98058..4a8bb25 100644
--- a/drivers/net/wireless/wl12xx/Kconfig
+++ b/drivers/net/wireless/wl12xx/Kconfig
@@ -74,4 +74,7 @@
 	  If you choose to build a module, it'll be called
 	  wl1271_sdio. Say N if unsure.
 
-
+config WL12XX_PLATFORM_DATA
+	bool
+	depends on WL1271_SDIO != n
+	default y