sed-opal: add IOC_OPAL_REACTIVATE_LSP.

sed-opal: add IOC_OPAL_REACTIVATE_LSP.

This adds the 'Reactivate' method as described in the
"TCG Storage Opal SSC Feature Set: Single User Mode"
document (ch. 3.1.1.1).

The method enables switching an already active SED OPAL2 device,
with appropriate firmware support for Single User Mode (SUM),
to or from SUM.

Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>