scarlet: support rearrangement of warm_reset

Newer servo headers may have warm_reset on pin 39,
add a config based on board selection to configure
yoshi header in the new way or old way.

BUG=b:64724237
TEST=Works on scarlet, works on reef config.

Change-Id: I399ecdda8f77578c415aa021d9d8af23876c4b37
Signed-off-by: Nick Sanders <nsanders@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/631190
Reviewed-by: Alexandru M Stan <amstan@chromium.org>
11 files changed