r8169: remove callback hw_start from struct rtl_cfg_info

After the latest changes we don't need separate functions
rtl_hw_start_8168 and rtl_hw_start_8101 any longer. This allows us to
simplify the code. For this change we need to move rtl_hw_start() and
rtl_hw_start_8169(). rtl_hw_start_8169() is unchanged.

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