b43: check for allocation failures

Add some error handling if the allocation fails.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/b43/bus.c b/drivers/net/wireless/b43/bus.c
index 6c63aec..8a10b82 100644
--- a/drivers/net/wireless/b43/bus.c
+++ b/drivers/net/wireless/b43/bus.c
@@ -83,7 +83,11 @@
 
 struct b43_bus_dev *b43_bus_dev_ssb_init(struct ssb_device *sdev)
 {
-	struct b43_bus_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	struct b43_bus_dev *dev;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return NULL;
 
 	dev->bus_type = B43_BUS_SSB;
 	dev->sdev = sdev;