The identifiers have been extracted from Realtek's drivers:
- version 8.002.00 of the r8168 driver
- version 6.002.00 of the r8169 driver
- version 1.002.00 of the r8101 driver

1. RTL_GIGA_MAC_VER_17 (8168Bf) is isolated from RTL_GIGA_MAC_VER_12 (8168Be)
   Both are still handled the same in rtl8169_set_speed_xmii and in
   rtl_set_rx_mode to avoid changes of behavior in this patch.

2. RTL_GIGA_MAC_VER_16 (8101Ec) is isolated from RTL_GIGA_MAC_VER_13 (8101Eb)
   Same thing as above with relation to rtl8169_set_speed_xmii,
   rtl_set_rx_mode and rtl_hw_start_8101.

3. The remaining new identifiers should not hurt.
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: Edward Hsu <edward_hsu@realtek.com.tw>