flash_ec: Add support for kitty
flash_ec: Add support for kitty

Make board kitty to use flash_stm32.

BUG=chrome-os-partner:33035
BRANCH=None
TEST=Run util/flash_ec on kitty, verify flashing
complete successfully.

Signed-off-by: Ken Chang <kenc@nvidia.com>
Reviewed-on: https://chromium-review.googlesource.com/224231
Reviewed-by: Randall Spangler <rspangler@chromium.org>
(cherry picked from commit 89a28fd46459612b1a3bc965933ba8de0802d2df)
Signed-off-by: Duncan Laurie <70662b43bc1a20b57ded72a2b08be88dd0da4841@chromium.org>

Change-Id: I302cfc85bfe5fa36fdf1a61d59b4dc21b36cc06a
Reviewed-on: https://chromium-review.googlesource.com/225745
Tested-by: Duncan Laurie <70662b43bc1a20b57ded72a2b08be88dd0da4841@chromium.org>
Reviewed-by: Duncan Laurie <70662b43bc1a20b57ded72a2b08be88dd0da4841@chromium.org>
Commit-Queue: Duncan Laurie <70662b43bc1a20b57ded72a2b08be88dd0da4841@chromium.org>

thehobn/ec,thehobn/ec,thehobn/ec,thehobn/ec