[SCSI] libfc: fix checking FC_TYPE_BLS

Its checked after skb freed, so instead have fh_type
cached and then check FC_TYPE_BLS against cached
fh_type value.

This wrong check was causing double exch locking as
reported by Bhanu at
https://lists.open-fcoe.org/pipermail/devel/2011-October/011793.html

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Tested-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>