net: phy: improve genphy_c45_read_link

Let's make genphy_c45_read_link behave the same as genphy_update_link
and set phydev->link in the function directly. This allows to simplify
the callers. In addition don't check further devices once we detect
that at least one device reports link as down.

v2:
- remove an unused variable

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>