[DM/BLOCK] Fixup DFS partition memory leak

Signed-off-by: GuEe-GUI <2991707448@qq.com>

components/drivers/block/partitions/dfs.c

@@ -49,5 +49,7 @@ rt_err_t dfs_partition(struct rt_blk_disk *disk)
         }
     }
 
+    rt_free(sector);
+
     return RT_EOK;
 }