servod.conf: add support for model

This adds an optional config MODEL= to servod.conf
Having this override allows differentiated servo
config based on model. This is cached, and passed
through as the --model arg to servod.

BUG=chromium:886955
TEST=startup works with and without arg. If present it's passed to servod.

Change-Id: I565382a91d25809ac70cd65f2ad6c132665e878b
Reviewed-on: https://chromium-review.googlesource.com/1288997
Commit-Ready: Nick Sanders <nsanders@chromium.org>
Tested-by: Nick Sanders <nsanders@chromium.org>
Reviewed-by: Justin TerAvest <teravest@chromium.org>
1 file changed