r8169: move common initializations to tp->hw_start

The chip-specific init code includes quite some calls which are
identical for all chips. So move these calls to tp->hw_start().

In addition move rtl_set_rx_max_size() a little to make sure it's
defined before it's used. Unfortunately the diff generated by git
is a little bit hard to read.

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