Log GPS data on pad after boost detect.

Log GPS data on pad after boost detect.

This wakes up the two GPS reporting tasks and gets them to report out
any existing GPS data to the log file. To make sure the timestamps in
that GPS data are accurate, this also records GPS time on receipt of
the GPS data instead of when that is logged.

Signed-off-by: Keith Packard <keithp@keithp.com>