Fix unbound variable access

The function _hwclock_ts() raises 2 types of exception: resume timestamp
earlier than threshold, and read error on power_manager timestamp file.
This change fixes an unbound variable access.

BUG=chromium-os:37843
TEST=manual

Change-Id: I10b81c859dbdd815a3bd9c2eb748540413273f12
Reviewed-on: https://gerrit.chromium.org/gerrit/41193
Reviewed-by: Brian Harring <ferringb@chromium.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Commit-Queue: Rong Chang <rongchang@chromium.org>
Tested-by: Rong Chang <rongchang@chromium.org>
1 file changed