flash_ec: add rammus board
flash_ec: add rammus board

This patch adds rammus to flash_ec script.

BUG=b:111579280
BRANCH=master
TEST=flash_ec --board rammus --image ec.bin

Change-Id: I30193835d1d3bb8097751ed0de0e2eb12264dd51
Signed-off-by: Zhuohao Lee <916bf7ddbf0565669e59e3cb2b613381a48066c0@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1149946
Reviewed-by: Furquan Shaikh <6be5c96c464778f89679b1062a2e0a6af93d2aa5@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec