[SCSI] libfcoe: add tracking FIP Virtual Link Failure count

Add tracking the Virtual Link Failure count when either we have found
the FCF as "aged" or we are receiving FIP Clear Virtual Link from the
FCF.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>