iwmc3200wifi: Return proper error for iwm_if_alloc

In the case of alloc_netdev_mq failure and kmalloc failure,
current implementation returns ERR_PTR(0).

As a result, the caller of iwm_if_alloc does not catch the error by IS_ERR
macro. Fix it by setting proper error code for ret variable in the failure
cases.
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwmc3200wifi/netdev.c

@@ -126,6 +126,7 @@ void *iwm_if_alloc(int sizeof_bus, struct device *dev,
 	ndev = alloc_netdev_mq(0, "wlan%d", ether_setup, IWM_TX_QUEUES);
 	if (!ndev) {
 		dev_err(dev, "no memory for network device instance\n");
+		ret = -ENOMEM;
 		goto out_priv;
 	}
 
@@ -138,6 +139,7 @@ void *iwm_if_alloc(int sizeof_bus, struct device *dev,
 				    GFP_KERNEL);
 	if (!iwm->umac_profile) {
 		dev_err(dev, "Couldn't alloc memory for profile\n");
+		ret = -ENOMEM;
 		goto out_profile;
 	}