firmware: Prevent showing "On reboot EC update may occur" on devices without EC.

For devices without EC ($ECID is empty), we should not alert use about potential
software sync (which won't occur).

Note startup info is also revised to show if EC is available.

BUG=chrome-os-partner:24216
TEST=emerge-panther chromeos-firmware-panther.
     chromeos-firmwareupdate --mode=autoupdate # no "On reboot..." message.

Change-Id: Id3c5d2c2a1fb406dbc071c3a0f1f98db58a50ac8
Reviewed-on: https://chromium-review.googlesource.com/187565
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Mohammed Habibulla <moch@google.com>
Commit-Queue: Hung-Te Lin <hungte@chromium.org>
1 file changed