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.
RI won't be accessible due to it being used by the kernel as an
interrupt source, so we can check the STATUS pin (CE only) which will
allow us to know precisely when the modem is shut down.
