[SCSI] libfc: discovery restart sequence error fix

When an RSCN is received during fabric discovery, it restarts.
After the restart, disc->seq_count was incremented, so when
the first frame was received, it was considered "out of sequence".
That left the state disc->active, preventing further discoveries.

Change to advance the sequence count before parsing, so that it
won't be changed after a potential restart.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>