Implement pckbc_xt_translation() in gsckbc. Thus, we can attach pckbd instead of

Implement pckbc_xt_translation() in gsckbc. Thus, we can attach pckbd instead of
gsckbd; the former will cause a proper translation page to be selected by
the keyboard.

Because of this, we no longer depend on the page the keyboard is left in
by the PDC (page 2 for all machines but the PrecisionBook, which is in
page 3), and there is no longer any need to use separate keyboard maps.