spec/parallels: fix a mistake

We have only one flag for now - Empty Image flag. The patch fixes unused
bits specification and marks bit 1 as usused.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>