Change the bdev_raid examine procedure to read the superblock from the
examined base bdev. If a valid superblock is found, re-create the
raid_bdev from it.
Change-Id: I4bd589647a207a216ecf0dec9baf11c5d691f5d5
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>