ip17xx: correct aneg_done return value

PHY core treats any positive return value as the auto-negotiation done
indication. Since we do not actually check any device register in this
callback then update it to return positive value with a neutral meaning
instead of the register flag to avoid  confusing for future readers.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>

target/linux/generic/files/drivers/net/phy/ip17xx.c

@@ -1334,7 +1334,7 @@ static int ip17xx_config_aneg(struct phy_device *pdev)
 
 static int ip17xx_aneg_done(struct phy_device *pdev)
 {
-	return BMSR_ANEGCOMPLETE;
+	return 1;	/* Return any positive value */
 }
 
 static int ip17xx_update_link(struct phy_device *pdev)