hatch: Add support for Kohaku

BUG=b:131265296
TEST=build mosys and test on Hatch_whl, the correct ROM size is
returned.

Change-Id: I2ec11d6f1a13d256b6548914e182ea43e19b1e86
Reviewed-on: https://chromium-review.googlesource.com/1584404
Commit-Ready: Philip Chen <philipchen@chromium.org>
Tested-by: Philip Chen <philipchen@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@chromium.org>
3 files changed