Add support for the FA-WWN (fabric assigned wwn) fabric switch feature.

(Fabric Assigned World Wide Port Name)
Signed-off-by: Joe Carnuccio <joe.carnuccio@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>