pscsi: fix REPORT LUNS handling

We need to assign spc_emulate_report_luns to the execute_cmd callback
and not execute it directly.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_pscsi.c

@@ -1001,7 +1001,8 @@ static int pscsi_parse_cdb(struct se_cmd *cmd)
 	 */
 	switch (cdb[0]) {
 	case REPORT_LUNS:
-		return spc_emulate_report_luns(cmd);
+		cmd->execute_cmd = spc_emulate_report_luns;
+		return 0;
 	case READ_6:
 	case READ_10:
 	case READ_12: