Cleaning up SIM hot swap

[carlo]

Hi Eric,

On Fri, 2017-07-07 at 16:11 -0700, Eric Caruso wrote:
> While trying to implement setup_sim_hot_swap for MBIM modems, I
> noticed that I am setting up and enabling unsolicited events for
> SUBSCRIBER_INFO type notifications, but not cleaning them up. This
> might not end up affecting the user since the destruction of the
> modem
> object will disconnect the signal handler, but it means I might be
> leaving the modem in a weird state when it's disabled or unplugged

consider that the modems might not keep this configuration after
reboot, unless you've explicitly saved it with a proper command. At
least, this is the behavior of Telit modems, whose plugin is the only
one that currently implements sim hot swap in modemmanager.