sh_eth: fix invalid context bug while calling auto-negotiation by ethtool

Since commit 35b5f6b1 ("PHYLIB: Locking fixes for PHY I/O
potentially sleeping") phy_start_aneg() function utilizes a mutex
to serialize changes to phy state, however the helper function is
called in atomic context.

The bug can be reproduced by running "ethtool -r" command, the bug
is reported if CONFIG_DEBUG_ATOMIC_SLEEP build option is enabled.

Fixes: dc19e4e5 ("sh: sh_eth: Add support ethtool")
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -2265,18 +2265,10 @@ static void sh_eth_get_regs(struct net_device *ndev, struct ethtool_regs *regs,
 
 static int sh_eth_nway_reset(struct net_device *ndev)
 {
-	struct sh_eth_private *mdp = netdev_priv(ndev);
-	unsigned long flags;
-	int ret;
-
 	if (!ndev->phydev)
 		return -ENODEV;
 
-	spin_lock_irqsave(&mdp->lock, flags);
-	ret = phy_start_aneg(ndev->phydev);
-	spin_unlock_irqrestore(&mdp->lock, flags);
-
-	return ret;
+	return phy_start_aneg(ndev->phydev);
 }
 
 static u32 sh_eth_get_msglevel(struct net_device *ndev)