scsi: libfc: Fix potential NULL pointer dereference in fc_lport_ptp_setup()

fc_lport_ptp_setup() did not check the return value of fc_rport_create()
which can return NULL and would cause a NULL pointer dereference. Address
this issue by checking return value of fc_rport_create() and log error
message on fc_rport_create() failed.

Signed-off-by: Wenchao Hao <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Simon Horman <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/libfc/fc_lport.c

···
 	}
 	mutex_lock(&lport->disc.disc_mutex);
 	lport->ptp_rdata = fc_rport_create(lport, remote_fid);
+	if (!lport->ptp_rdata) {
+		printk(KERN_WARNING "libfc: Failed to setup lport 0x%x\n",
+			lport->port_id);
+		mutex_unlock(&lport->disc.disc_mutex);
+		return;
+	}
 	kref_get(&lport->ptp_rdata->kref);
 	lport->ptp_rdata->ids.port_name = remote_wwpn;
 	lport->ptp_rdata->ids.node_name = remote_wwnn;