r8169: factor out PHY init sequence adjusting 10M and ALDPS

Few chip versions use the same sequence to adjust 10M and ALDPS, so
let's factor it out. This patch also fixes a (most likely) typo in
rtl8168g_1_hw_phy_config. There bit 8 in reg 0x14 on page 0x0bcc
was set and not cleared. According to the vendor driver this bit
needs to be cleared in all cases.

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