[ALSA][ALL] use custom alsa mixer default for all boards

The file asound.state was originally copied from: meta-freescale/recipes-bsp/alsa-state/alsa-state/imx-generic-bsp/asound.state

It is used as fallback on all boards, replace it with ours in general since we now have set specific names for the various audio cards to avoid collisions that would apply wrong states for different codec configurations.