cifs: return proper error code in statfs(2)

In cifs_statfs(), if server->ops->queryfs is not NULL, then we should
use its return value rather than always returning 0.  Instead, use rc
variable as it is properly set to 0 in case there is no
server->ops->queryfs.
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifsfs.c

@@ -290,7 +290,7 @@ cifs_statfs(struct dentry *dentry, struct kstatfs *buf)
 		rc = server->ops->queryfs(xid, tcon, cifs_sb, buf);
 
 	free_xid(xid);
-	return 0;
+	return rc;
 }
 
 static long cifs_fallocate(struct file *file, int mode, loff_t off, loff_t len)