[SCSI] libfc: add local port hook for provider session lookup

The target provider needs a per-instance lookup table
or other way to lookup sessions quickly without going through
a linear list or serializing too much.

Add a simple void * array indexed by FC-4 type to the fc_lport.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Committed-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>