lenovo/t400: Rewrite dock from t60

Old dock.c copied from x201 was incorrect. Do a rewrite of t60 dock
code as pnp devices.

Fixes USB and serial on the dock, if it is already connected when
computer is powered on. DVI and ethernet worked without this patch.

Hot-plug is yet to be fixed.

Change-Id: Ib20a0eff10d0cde92dd089baf4fca28b117dc999
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/18054
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/ec/lenovo/h8/h8.h

@@ -28,9 +28,7 @@ int h8_ultrabay_device_present(void);
 u8 h8_build_id_and_function_spec_version(char *buf, u8 buf_len);
 void h8_usb_always_on(void);
 
-#if !IS_ENABLED (CONFIG_H8_DOCK_EARLY_INIT)
 void h8_mainboard_init_dock (void);
-#endif
 
 /* EC registers */
 #define H8_CONFIG0 0x00