Do not leak eventfd's for RFCOMM/AVDT/L2CAP

Various users of fixed_queue's do not free the lists properly after
using them. As a result two event fd's leak for each fixed_queue that
is not free'd, as fixed_queue contains two semaphores.

This can lead to run-away file descriptor allocation and an eventual
hard limit leading to various undefined behaviours.

Bug: 27731859
Change-Id: If9ce64b711083bf474d217aa537220065722ad3a