faft: Better comment about the new_ec parameter on firmware_UpdataECBin test

Make it more clear when the new_ec parameter is not specified.

BUG=chrome-os-partner:12997
TEST=Run the following command:
$ run_remote_tests.sh --remote=$IP firmware_UpdateECBin/control.dev

It prints out the error messages:
INFO    : Test results:
-------------------------------------------------------------
firmware_UpdateECBin.dev        [  FAILED  ]
firmware_UpdateECBin.dev        ERROR: Should specify a new_ec image for update,
like: run_remote_tests.sh --args "new_ec=ec_autest_image.bin". The ec_autest_ima
ge.bin file is included in the firmware_from_source.tar.bz2.

Change-Id: I3641c5b384b6a1e5fe6177a72bd0d1f1825daaf7
Reviewed-on: https://gerrit.chromium.org/gerrit/32370
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
3 files changed