Increment timeout before pppd gives up when trying to get an IP address.
Needed as some times this modem does not respond to PPP frames, but we
want NetworkManager to wait a bit to stop pppd - otherwise the port is
not properly closed and does not respond to AT commands anymore.
Previously, probing or not the commands depended on a race condition,
and, besides, we need the AT ports for implementing workarounds for
Sierra HL7588. Therefore, we make sure we always probe the AT ports in
the Dell plugin, even when an MBIM port has already been detected.
Sent AT+CGACT=1,3 command for Sierra HL7588 on connection as a
workaround for buggy modem firmware. This makes sure vzwinternet
is activated.
This workaround is executed for both Sierra and Dell VID/PID, but
an additional twist is needed for the later, as Dell reused same
VID/PID for a Telit modem, so we additionally check the ouput of
AT+CGMM.
