net: bgmac: Fix return value check for fixed_phy_register()

The fixed_phy_register() function returns error pointers and never
returns NULL. Update the checks accordingly.

Fixes: c25b23b ("bgmac: register fixed PHY for ARM BCM470X / BCM5301X chipsets")
Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Ruan Jinjie

drivers/net/ethernet/broadcom/bgmac.c

@@ -1448,7 +1448,7 @@ int bgmac_phy_connect_direct(struct bgmac *bgmac)
 	int err;
 
 	phy_dev = fixed_phy_register(PHY_POLL, &fphy_status, NULL);
-	if (!phy_dev || IS_ERR(phy_dev)) {
+	if (IS_ERR(phy_dev)) {
 		dev_err(bgmac->dev, "Failed to register fixed PHY device\n");
 		return -ENODEV;
 	}