arm64/mpam: Fix compile warning

hulk inclusion
category: bugfix
bugzilla: 34278
CVE: NA

-------------------------------------------------

Set dentry before goto error handling branch.

fs/resctrlfs.c: In function ‘resctrl_mount’:
fs/resctrlfs.c:419:9: warning: ‘dentry’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  return dentry;
         ^~~~~~

Fixes: 67adc53a ("arm64/mpam: resctrl: Use resctrl_group_init_alloc() for default group")
Signed-off-by: NWang ShaoBo <bobo.shaobowang@huawei.com>
Reviewed-by: NJian Cheng <cj.chengjian@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>

fs/resctrlfs.c

@@ -354,8 +354,10 @@ static struct dentry *resctrl_mount(struct file_system_type *fs_type,
 	}
 
 	ret = resctrl_group_init_alloc(&resctrl_group_default);
-	if (ret < 0)
+	if (ret < 0) {
+		dentry = ERR_PTR(ret);
 		goto out_schema;
+	}
 
 	ret = resctrl_group_create_info_dir(resctrl_group_default.kn, &kn_info);
 	if (ret) {