altoslib/altosui/telegps: Change log size configuration

* Use new log-space value provided by firmware when available.

* Divide that up into 1-8 flights and offer those sizes as options to
  the user instead of a fixed set of sizes.

* Show how many flights each selection will store

* This also checks values provided by the user

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