[SCSI] libfc: fix mm leak in handling incoming request for target discovery

When handling incoming request, if the operation code carried by the
received frame is not RSCN, the frame should be freed as in the RSCN
case, or there is memory leakage.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <jbottomley@parallels.com>