google/slippy: consolidate variants' common mainboard.asl code

Move code common code from each variant's mainboard.asl into
common ACPI code for all variants (like google/auron).  This also
adds the _PRW method for the LID0 device for falco and peppy, which
omitted the function  when they were originally upstreamed.

See Chromium commit c8b41f7, falco: Add _PRW for LID0 ACPI Device

Change-Id: I7f5129340249a986f5996af37c01ccbde8d374e8
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/18368
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
6 files changed