audio_route: fix crash with unsupported control types

Check if control type is supported before accessing xxx_value
fields in mixer_state structure.

Also remove unused parameter warning.

Bug: 12871072.
Change-Id: I64c7d5e16728e3502f1fcd0a40658b72ec7acbe7
Merge tag 'android-4.4.3_r1' into HEAD

Android 4.4.3 release 1
[1/3] AudioEffects: Add center frequency param to bassboost

Change-Id: Ia47a3f679a82392232b33b72e8dbd3b2545ee109
[2/3] audio_effects: Add a stereo widening effect

Change-Id: I0dd68fef857e8a031f52a63a81c642cb930419c6