[SCSI] libfcoe: Incorrect CVL handling for NPIV ports

[SCSI] libfcoe: Incorrect CVL handling for NPIV ports

Host doesnt handle CVL to NPIV instantiated ports correctly.
- As per FC-BB-5 Rev 2 CVLs with no VN_Port descriptors shall be treated as
  implicit logout of ALL vn_ports.
- CVL for NPIV ports should be handled before physical port even if descriptor
  for physical port appears before NPIV ports

Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <jbottomley@parallels.com>