lynxpoint: Add function for checking for LP chipset

Add a helper function pch_is_lp() that will return 1 if
the current chipset is of the new "low power" variant used
with Haswell ULT.

Additionally these functions are added to SMM so it can
be used there.

Change-Id: I9acdea2c56076cd8d9627aba66cf0844c56a38fb
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/2811
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
3 files changed