scsi: qla2xxx: Remove unnecessary NULL check

The list iterator can't be NULL so this check is not required.  Removing
the check silences a Smatch warning about inconsistent NULL checking.

    drivers/scsi/qla2xxx/qla_dfs.c:371 qla_dfs_tgt_counters_show()
    error: we previously assumed 'fcport' could be null (see line 372)

Link: https://lore.kernel.org/r/YAkaaSrhn1mFqyHy@mwanda
Acked-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>