[SCSI] libfc: Fixing a memory leak when destroying an interface

When an fcoe interface is being destroyed; in the process the
fcoe driver will try to release all the resources it had allocated
for that interface including rports. But, it seems that it does not
release the reference held for the name server rport in that process
resulting into a memory leak. This patch fixes that memory leak.

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