altos: Split out gps display function to separate file

altos: Split out gps display function to separate file

Take the gps_dump function from ao_gps_skytraq.c and move it to a new
file so it can be shared with the u-blox driver. That affects every
skytraq and u-blox user as they need to include the new file.

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