grouper: Better background gradients

Now lots of backgrounds look a bit ugly.
Using another dithering mode produces better gradients

Change-Id: I1907f02cb3c0c96ae7337d9eda17e7b39bf86db7
Enable USB audio module

Required for userland usb audio support (framework patches are pending)

Change-Id: Ib4c4775e8d2fb8b20f876f4cd51a58b745693442
Merge branch 'cm-10.2' of git://github.com/CyanogenMod/android_kernel_asus_grouper into cm-10.2