Replace ax25_to_str and get_ax25_name with address_to_str.

Change-Id: I74ddb6fc629ef32b217dede7a3ba652cbbf5ab12
Reviewed-on: https://code.wireshark.org/review/5932
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com>
Reviewed-by: Michael Mann <mmann78@netscape.net>