Don't set Interval by setting TimeRemaining

This change allows one to set the TimeRemaining as a one-time shot,
and also allows more straightforward control.

-Changing the Interval doesn't reset the watchdog or update the
TimeRemaining.
-Changing the TimeRemaining doesn't set the Interval for future
cycles.

Change-Id: I03a3cdb9cc9e5c4bc034dc86d2b4324a5a4b7243
Signed-off-by: Patrick Venture <venture@google.com>
2 files changed