entd: Fix problem where a future date setting causes TPM token to be cleared often

Change-Id: Icd14783f08c6761c74a35cec10821e3e97ce74ae

BUG=chrome-os-partner:2227
TEST=gmerge to device, set file to future, see .tpm directory persist

Review URL: http://codereview.chromium.org/6312172
1 file changed