r8169: remove print_mac_version

The syslog message printed on driver load allows to easily identify
the mac version number (based on chip name and XID). So we don't
need this extra debug message which is wrong anyway because e.g.
RTL_GIGA_MAC_VER_01 has value 0.

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