This is the port to git master of the following commit:
commit d1be19d231a395339b1f452d1a30b73ea77ad528
Author: Dan Williams <dcbw@redhat.com>
Date: Tue Aug 28 21:58:43 2012 -0500
sierra: fix CSQ handling on APP1 port
The APP1 port doesn't always prefix its replies with <CR><LF> which
runs afoul of the built-in echo removal. Since Sierra modems are on
the whole well-behaved WRT echo removal, just disable it on the
secondary ports. Only changes behavior for PPP-based devices since
they are the only ones that use the APP1 ports.
Aleksander Morgado
b4e0fa3d89