When we do frequent same subsystem add/delete,
we will face the adding issue. For example,
1 Add subsystem A
2 Delete subsystem A
3 Add subsystem A (Fail in this step).
The reason is that we did not correctly free
the listener resources of subsystems, and this patch
can solve this issue.
Change-Id: I6765a306a3f10c9a0f38c95dbba12e2a4073e705
Signed-off-by: Ziye Yang <ziye.yang@intel.com>