ibmvnic: Correct return code checking for ibmvnic_init during probe

The update to ibmvnic_init to allow an EAGAIN return code broke
the calling of ibmvnic_init from ibmvnic_probe. The code now
will return from this point in the probe routine if anything
other than EAGAIN is returned. The check should be to see if rc
is non-zero and not equal to EAGAIN.

Without this fix, the vNIC driver can return 0 (success) from
its probe routine due to ibmvnic_init returning zero, but before
completing the probe process and registering with the netdev layer.

Fixes: 6a2fb0e99f9c (ibmvnic: driver initialization for kdump/kexec)
Signed-off-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -3726,7 +3726,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 
 	do {
 		rc = ibmvnic_init(adapter);
-		if (rc != EAGAIN) {
+		if (rc && rc != EAGAIN) {
 			free_netdev(netdev);
 			return rc;
 		}