fix dfs statfs fullpath leak

components/dfs/dfs_v2/src/dfs_fs.c

@@ -650,6 +650,8 @@ int dfs_statfs(const char *path, struct statfs *buffer)
         }
     }
 
+    rt_free(fullpath);
+
     return ret;
 }
 
@@ -723,4 +725,4 @@ int dfs_filesystem_get_partition(struct dfs_partition *part,
     return RT_EOK;
 }
 
-/* @} */
+/* @} */