Audio latency reduction and configuration

Add af.fast_track_multiplier=1 to reduce audio output latency.
This device has low scheduling jitter and can handle this.

Allow period sizes to be configured by properties, for testing.

Change-Id: If37bc5c529cef4f63ddc878c6e428f4a9dd1dd1b
diff --git a/device.mk b/device.mk
index da6e64e..258f0d5 100644
--- a/device.mk
+++ b/device.mk
@@ -168,7 +168,8 @@
     ro.hwui.text_small_cache_height=1024 \
     ro.hwui.text_large_cache_width=2048 \
     ro.hwui.text_large_cache_height=1024 \
-    ro.hwui.disable_scissor_opt=true
+    ro.hwui.disable_scissor_opt=true \
+    af.fast_track_multiplier=1
 
 # setup dalvik vm configs.
 $(call inherit-product, frameworks/native/build/tablet-10in-xhdpi-2048-dalvik-heap.mk)