net: phy: switch remaining users to phy_(read|write)_mmd()

Switch everyone over to using phy_read_mmd() and phy_write_mmd() now
that they are able to handle both Clause 22 indirect addressing and
Clause 45 direct addressing methods to the MMD registers.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
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>