Make hal_allocator use hal_attribute_hwservice.

If you can get or serve the hal allocator interface,
you should be a hal_allocator_client or
hal_allocator_server.

Bug: 80319537
Test: boot aosp_walleye and (sanity) take photos
Change-Id: Iea14c67c4aa56df7a74ebdb17e99b78b1d3aa105

public/hal_allocator.te

 # HwBinder IPC from client to server
 binder_call(hal_allocator_client, hal_allocator_server)
 
-add_hwservice(hal_allocator_server, hidl_allocator_hwservice)
-allow hal_allocator_client hidl_allocator_hwservice:hwservice_manager find;
+hal_attribute_hwservice(hal_allocator, hidl_allocator_hwservice)
 allow hal_allocator_client hidl_memory_hwservice:hwservice_manager find;