Most of the modem issues follow a (incomplete) USB device reset. Instead
of relying solely on the existing timer, this patch adds a udev monitor
which resets the modem as soon as its associated USB device is reset,
which greatly improves recovery time.
This patch adds a 3s delay when resetting the modem during which we
avoid triggering a new reset. This makes sure we don't trigger a reset
twice in a row.
It also disables any related running timer to avoid being re-triggered
unnecessarily.
