drivers/ec: Return VBERROR_SUCCESS on successful TCPC FW update

TCPC chips request EC Reboot to RO under 2 different situation:
1) to unlock the concerned remote_bus tunnel, if already in locked state
2) to get reset after the FW update is applied successfully.
Returning the same error code in these different situation is ambiguos.
Update the TCPC chips drivers to return VBERROR_SUCCESS on successful FW
update, so that vboot can differentiate the situation and take
appropriate action.

BUG=b:128820536,b:119046668
BRANCH=None
TEST=Boot to ChromeOS. Force a TCPC FW update and ensure that the EC
reboots to RO after a successful TCPC update.

Cq-Depend: chromium:1627302
Change-Id: I519e72e33a372763ef7d7073a2a615acdcb011fe
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1625866
Tested-by: Karthikeyan Ramasubramanian <kramasub@chromium.org>
Commit-Ready: Karthikeyan Ramasubramanian <kramasub@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
3 files changed