scsi: lpfc: lpfc_attr: Fix Use plain integer as NULL pointer

Replace assignment of 0 to pointer with NULL assignment.

Link: https://lore.kernel.org/r/20191024025726.GA31421@sauravSigned-off-by: Saurav Girepunje <saurav.girepunje@gmail.com>
Acked-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/lpfc/lpfc_attr.c

@@ -1644,7 +1644,7 @@ lpfc_set_trunking(struct lpfc_hba *phba, char *buff_out)
 {
 	LPFC_MBOXQ_t *mbox = NULL;
 	unsigned long val = 0;
-	char *pval = 0;
+	char *pval = NULL;
 	int rc = 0;
 
 	if (!strncmp("enable", buff_out,