[SCSI] qla2xxx: Implement FCP priority tagging for 82xx adapters.

This provides a capability to set a priority in the FCP packet.

Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: Chad Dupuis <chad.dupuis@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>