video/exynos: dp: Add reporter to log dp errors

video/exynos: dp: Add reporter to log dp errors

This patch adds an error reporter work function to check the error count
from DPCD every 60 seconds and report any errors that have occurred in
the last minute. This will hopefully give us an indication about how
frequently we're getting screen glitches.

BUG=chrome-os-partner:12498
TEST=Tested on flickery snow, saw the errors being printed to logs

Change-Id: Idba96f63f0829c55f3c6378c399403c9de7dc123
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/30012
Reviewed-by: Doug Anderson <dianders@chromium.org>