target/tcm_fc: Remove a set-but-not-used variable

This was detected by building with W=1.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jth@kernel.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>