Configs: remove audio sink buffer size property

Use the default value of 500 for the audio sink buffer
size in msec when calculating the frame count for
playback tracks.
Add property to be used as multiplier when calculating
the client heap size in audioflinger

CRs-Fixed: 1073831
Change-Id: I630ffb80f3e469509dc66417e1db8f5cf7fc7f1c