net: phy: clean up PHY ID reading

Rearrange the code to read the PHY IDs, so we don't call get_phy_id()
only to immediately call get_phy_c45_ids().  Move that logic into
get_phy_device(), which results in better readability.

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>