cros_ec: Handle different I2C adapter names

The I2C adapter name changed between 3.4 and 3.8, replacing
underscores (_) with dashes (-).

BUG=chrome-os-partner:23524
BRANCH=none
TEST=tested on Snow with kernel 3.4 and 3.8

Change-Id: Ib2a191294424629cfd9a5cebc401c06747a2585f
Reviewed-on: https://chromium-review.googlesource.com/174928
Tested-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Commit-Queue: David Hendricks <dhendrix@chromium.org>
1 file changed