DO NOT MERGE - audio effects: fix heap overflow

Check consistency of effect command reply sizes before
copying to reply address.

Also add null pointer check on reply size.
Also remove unused parameter warning.

CYNGNOS-446
Bug: 21953516.
Change-Id: I4cf00c12eaed696af28f3b7613f7e36f47a160c4
(cherry picked from commit 8fd5331e)