i9500: Add audio.r_submix.default for casting

Change-Id: Ia2fc3b8a7cd8cedaabeef345c0044352400f81bc
Signed-off-by: zachd <runandhide05@gmail.com>
Merge pull request #49 from CyanogenMod/cm-11.0

i9500: Add audio.r_submix.default for casting