Updates to remote control client (un)registration

Iterate over the remote control stack from top to bottom
 when (un)registering a remote control client (RCC).
When unregistering an RCC, stop traversing the stack when
 match found. If match was at top of the stack, update
 the remote control display (RCD).

Change-Id: If64acf102bdf328085d707f9e0f7e86cf4d4001a