Adding Telit ME310G1-WW support

[Mark Deneen]

Hi!

I have a Telit ME310G1-WW cell modem which is supported in newer
(5.5.x) kernels with the option driver.  ModemManager (1.12.6, will
try to test newer versions) almost works, but it appears to be a modem
quirk which prevents MM from detecting that it is connected.  Here's a
few log entries showing the issue:

Feb  7 17:19:55 sama5d27 daemon.debug ModemManager[783]: <debug>
(ttyUSB2): --> 'ATD*99***6#<CR>'
Feb  7 17:19:55 sama5d27 daemon.debug ModemManager[783]: <debug>
(ttyUSB2): <-- '~\255}#\192!}!(} }9}"}&} } } }
}#}%\194#}%}%}&s\168\133;}'}"}(}"0O~'

It selects the appropriate context (6) and issues the ATD command, but
the modem responds with PPP data and never prints out "CONNECT", and
MM eventually times out waiting for a response.

This modem is very new, and I likely have one of a few which are out
in the wild, so there's a chance that this may be corrected at some
point by Telit.  With that being said, I was considering adding a
GRegex to mm-serialparsers.c which matches PPP escape sequences in
order to detect the connection.  Does this seem like a valid approach?

All the best,
Mark Deneen