braswell: acpi: Allow DPTF thresholds to be defined at board-level

Similar to Skylake, allow braswell mainboards to override the default
DPTF thresholds.

BUG=chrome-os-partner:43884
TEST=Build for Strago
BRANCH=Strago

Change-Id: Id2574e98c444b8bf4da8ca36f3eeeb06568e78e0
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 799a7006e8fcacfea8e8e0de5c99c3ce3c4ac34f
Original-Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Original-Change-Id: If69627163237674a28fb8a26b4ce1886e5dbfc17
Original-Reviewed-on: https://chromium-review.googlesource.com/296033
Original-Commit-Ready: Shawn N <shawnn@chromium.org>
Original-Tested-by: Shawn N <shawnn@chromium.org>
Original-Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/11546
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
2 files changed