Sholes mobile iface comes/goes - handle the reset

The byte counter for the iface goes to zero when it comes back.  Catch that and
do the complex math to correct.

Also add a log entry telling us our desired throttle index.

Lastly, reset the sec/msec part of our reset time so that one calc will == another and not
be off by little bits.

bug:25494925
Change-Id: I99525b72a76316a8e601ceb457ca202fae040bae