Do not print tg_pt_gp->tg_pt_gp_valid_id if we already know that it is zero.

Link: https://lore.kernel.org/r/20210415220826.29438-20-bvanassche@acm.org
Cc: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>