Fix issue 3509396: AudioEffect.getParameter JAVA.

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