nfsd: Fix error return code in nfsd_file_cache_init()

Fix to return PTR_ERR() error code from the error handling case instead of
0 in function nfsd_file_cache_init(), as done elsewhere in this function.

Fixes: 65294c1f("nfsd: add a new struct file caching facility to nfsd")
Signed-off-by: Huang Guobin <huangguobin4@huawei.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/filecache.c

@@ -685,6 +685,7 @@ nfsd_file_cache_init(void)
 	if (IS_ERR(nfsd_file_fsnotify_group)) {
 		pr_err("nfsd: unable to create fsnotify group: %ld\n",
 			PTR_ERR(nfsd_file_fsnotify_group));
+		ret = PTR_ERR(nfsd_file_fsnotify_group);
 		nfsd_file_fsnotify_group = NULL;
 		goto out_notifier;
 	}