Removed dead/buggy code in AudioEffect.getParameter() and
AudioEffect.command() that was meant to return the actual length of
meaningful data in the returned parameter or command reply.
This is replaced by the method return status indicating this length when
positive (negative return codes still indicate the same errors as before).
Modified automated AudioEffect tests accordingly.
Change-Id: Ie89617f912766b8dee73b81f92af9c48027c982d
602b3286ff