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.

Change-Id: I9005d4760e55f0798d576bd4507700e198900311
audio_route: Add APIs to update mixer based on path

audio_route_apply_and_update_path
audio_route_reset_and_update_path

These routines allows updating the mixer controls for
just the specified path. The controls will be updated
in the order listed in the XML file.

Change-Id: If193bc047ccbb8c6497926d6181c5c4541a9d6aa
CRs-Fixed: 581453