block: add a transfer rate for floppy types

block: add a transfer rate for floppy types

Floppies must be read at a specific transfer rate, depending of its own format.
Update floppy description table to include required transfer rate.

Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>