drivers/i2c/cros_ec_tunnel: Add support to locate TCPC chip info

Add a command to EC and an associated helper function to retrieve remote
bus information for TCPC ports.

BUG=b:128820536,b:119046668
BRANCH=None
TEST=Boot to ChromeOS. Ensure that EC responds with I2C port
information.
2019-05-23 11:30:43 [52.157015 HC 0x126]

Cq-Depend: chromium:1614582
Change-Id: If423d5f0ea569dba0a74e6a86d47612b1dfa1487
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1622589
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