wl1271: make ref_clock configurable by board

The wl1271 device is using a reference clock that may change
between board to board.

Make the ref_clock parameter configurable by board settings
instead of having a hard coded value in the sources.

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/wl1271_spi.c b/drivers/net/wireless/wl12xx/wl1271_spi.c
index de56d8d..ced0a9e 100644
--- a/drivers/net/wireless/wl12xx/wl1271_spi.c
+++ b/drivers/net/wireless/wl12xx/wl1271_spi.c
@@ -372,6 +372,8 @@
 		goto out_free;
 	}
 
+	wl->ref_clock = pdata->board_ref_clock;
+
 	wl->irq = spi->irq;
 	if (wl->irq < 0) {
 		wl1271_error("irq missing in platform data");