[coreboot] TianoCore: Get PS/2 keyboard working in UefiPayloadPkg

[Paul Menzel]

Dear coreboot folks,

Those of you, who missed it in #[e-mail] and do
not monitor the TianoCore bug tracker, Greg (myfreeweb) posted
instructions on how to get PS/2 working in UefiPayloadPkg [1].

Kind regards,

Paul

[1]: https://bugzilla.tianocore.org/show_bug.cgi?id=2241#c1