cmhw: remove button backlight tunable

This partially reverts commit 6730ecdee4237e7ee7f31785d80f567535930b28.

Backlight control was hooked to PowerManager.

Change-Id: Id08d7bcd28bf61337cc1da27bcc1b1f2257cdd3d
cmhw: enable usb charging tunable

Needs patches to opt/hardware and settings. Not much point
in submitting this upstream because disabling USB
charging is ZTE addition. Some might even argue usefulness
of such feature. :P

Change-Id: I77d8d3a768aa88fb74e4b199953d5ffee2ef3cc2
libaudio: force 8khz sample rate for VoIP input

Fixes muted mic in Viber.

Change-Id: Ie037ce633aa1fb532213f4a5d92f0ec71de81484
update patches