Add bolt as another slippy derivative and add some GPIOs

This just gives basic board support and adds some GPIOs
that are the memory strap for bolt/samus.

It also adds a new spd_index function for bolt/samus as
those use different GPIOs for the ram id.

BUG=chrome-os-partner:22996,chrome-os-partner:22419
BRANCH=bolt
TEST=emerge-bolt mosys

Change-Id: I1302dcc8580c035c45dbd31d761dda61f36d5925
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/171920
Reviewed-by: David Hendricks <dhendrix@chromium.org>
3 files changed