int sd_remove (struct device * dev);
sd_probe) is detached from the system. It is called (potentially multiple times) during sd module unload.
this function is invoked from the scsi mid-level. This function potentially frees up a device name (e.g. /dev/sdc) that could be re-used by a subsequent sd_probe. This function is not called when the built-in sd driver is ``exit-ed''.