Audio effects: aligned Equalizer API argument types on OpenSL ES SLEqualizerItf.

Modified types of some arguments and returned values of the Equalizer class from int to short
to match those defined by OpenSL ES SLEqualizerItf interface.

Also fixed a problem with set properties in equalizer engine implementation.

Change-Id: I75894bad0cb67b01c18ca5e22f9687e75ee491b8