target: simplify target_fabric_make_lun error path

Coverity complained that lun_cg has been dereferenced in all paths
leading to NULL check.  It didn't mention that only a single path could
lead there and the code can be simplified even further.
Signed-off-by: Joern Engel <joern@logfs.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_fabric_configfs.c

@@ -911,15 +911,12 @@ static struct config_group *target_fabric_make_lun(
 				GFP_KERNEL);
 	if (!port_stat_grp->default_groups) {
 		pr_err("Unable to allocate port_stat_grp->default_groups\n");
-		errno = -ENOMEM;
-		goto out;
+		kfree(lun_cg->default_groups);
+		return ERR_PTR(-ENOMEM);
 	}
 	target_stat_setup_port_default_groups(lun);
 
 	return &lun->lun_group;
-out:
-	kfree(lun_cg->default_groups);
-	return ERR_PTR(errno);
 }
 
 static void target_fabric_drop_lun(