samus: Add PD interface support

Enable the PD interface and command list to get 'mosys pd info'
command supported.

BUG=chrome-os-partner:31130
BRANCH=samus
TEST=test "mosys pd info" on samus

Change-Id: Iabf3f2550f57e9c4f5a7df8446d08d1faa231f10
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/213315
Reviewed-by: David Hendricks <dhendrix@chromium.org>
3 files changed