cc2520: set the default fifo pin value from platform data

When the device tree support is disabled, the fifo_pin is uninitialized,
this patch will set the fifo_pin value based on platform data

Signed-off-by: Yong Li <sdliyong@gmail.com>
Acked-by: Varka Bhadram <varkabhadram@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/drivers/net/ieee802154/cc2520.c b/drivers/net/ieee802154/cc2520.c
index 613dae5..c5b54a1 100644
--- a/drivers/net/ieee802154/cc2520.c
+++ b/drivers/net/ieee802154/cc2520.c
@@ -833,6 +833,7 @@
 		if (!spi_pdata)
 			return -ENOENT;
 		*pdata = *spi_pdata;
+		priv->fifo_pin = pdata->fifo;
 		return 0;
 	}