net: bcmgenet: only update UMAC_CMD if something changed

The link adjustment callback can be called as frequently as desired
by the PHY library, as such, let's avoid doing a Read/Modify/Write
sequence if nothing changed, since these register accesses can be
expensive.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmmii.c

@@ -136,17 +136,18 @@ static void bcmgenet_mii_setup(struct net_device *dev)
 		/* pause capability */
 		if (!phydev->pause)
 			cmd_bits |= CMD_RX_PAUSE_IGNORE | CMD_TX_PAUSE_IGNORE;
+	}
 
+	if (status_changed) {
 		reg = bcmgenet_umac_readl(priv, UMAC_CMD);
 		reg &= ~((CMD_SPEED_MASK << CMD_SPEED_SHIFT) |
 			       CMD_HD_EN |
 			       CMD_RX_PAUSE_IGNORE | CMD_TX_PAUSE_IGNORE);
 		reg |= cmd_bits;
 		bcmgenet_umac_writel(priv, reg, UMAC_CMD);
-	}
 
-	if (status_changed)
 		phy_print_status(phydev);
+	}
 }
 
 void bcmgenet_mii_reset(struct net_device *dev)