Unloading the driver doesn't clear the interrupts

Created by: gvarlet

When the user reboots and any other MDIS modules are loaded, if its interrupt is shared with other MDIS devices, MDIS has then a connected handler to this IRQ, but no responding driver. If a character is received at this time by the z055 controller, it issues an IRQ, which is handled by no one, leading to a freeze.