-allow to open RAW_PART, even if readdisklabel() doesn't like what it sees
-fix PERIPH_MEDIA_LOADED toggling on every other open attempt
-Don't reset PERIPH_REMOVABLE if prevent/allow fails - this is normal
for floppy drives. The flag is required for media change detection.
Honour XS_CTL_SILENT for the "no door lock" printouts, and set that flag
where scsipi_prevent() is called during open/close.
Tested with a USB floppy and a USB cardreader.
bf84051422