[coreboot] X60: add support for Ultrabase X6

[Sven Schnelle]

Hi List,

these patches add support for the Ultrabase X6 to the Lenovo X60 port.
while we already did initialize a Docking station in romstage to have
serial output, these patches move those code to dock.c, which is used
in romstage and SMM for Docking/Undocking.

This patch only adds the basic ACPI code for getting the Fn-F9 key to
work, all other required ACPI code will be submitted later.