netdev: octeon: fix return value check in octeon_mgmt_init_phy()

In case of error, the function of_phy_connect() returns NULL
pointer not ERR_PTR(). The IS_ERR() test in the return value
check should be replaced with NULL test.

dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch)
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/octeon/octeon_mgmt.c

@@ -722,10 +722,8 @@ static int octeon_mgmt_init_phy(struct net_device *netdev)
 				   octeon_mgmt_adjust_link, 0,
 				   PHY_INTERFACE_MODE_MII);
 
-	if (IS_ERR(p->phydev)) {
-		p->phydev = NULL;
+	if (!p->phydev)
 		return -1;
-	}
 
 	phy_start_aneg(p->phydev);