Quectel GNSS errors addition

[Peter Naulls]

I'm looking at the errors returned by some of the GPS operations.  e.g.:

/usr/bin/mmcli -m 0 --command=AT+QGPSEND
error: command failed: 
'GDBus.Error:org.freedesktop.ModemManager1.Error.MobileEquipment.Unknown: 
Unknown mobile equipment error: 505'

These are documented here:

https://sixfab.com/wp-content/uploads/2018/09/Quectel_EC25EC21_GNSS_AT_Commands_Manual_V1.1.pdf

This document is allegedly confidential, but I found it with a Google search. 
Anyway, I can't cut and paste the text easily, but the errors and descriptions
are on page 30, and run 501-549.

I can probably put together a patch, but I wanted to let you guys know.


Regards.