USB Storage: add rio karma eject support

This changeset from Keith Bennett (via Bob Copeland) moves the Karma
initializer to its own file and adds trapping of the START_STOP command to
enable eject of the device.

Signed-off-by: Keith Bennett <keith@mcs.st-and.ac.uk>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>