[SCSI] fcoe: Allow exposing FDMI attributes via sysfs

Allow FDMI attributes to be exposed via the fc_host
class object for the fcoe driver.

Signed-off-by: Neerav Parikh <neerav.parikh@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Acked-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>