r8169: merge handling of chip versions 12 and 17 (RTL8168B)

It's not clear why XID's 380 and 381..387 ever got different chip
version id's. VER_12 and VER_17 are handled exactly the same.
Therefore merge handling under the VER_17 umbrella.

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