apn: Updating Movistar Argentina APN

This change updates the APN settings, removing the proxy and the port. 
  This, according to movistar itself, makes the connection slower and 
  will be shut down soon.

More info on their forum: 
https://foro.movistar.com.ar/threads/43044-NOVEDAD-Apagado-de-Proxy

Change-Id: I705e6ed2237503ee67c7371bf3595b461dfbbd9c