mixout: Convert component to use the module adapter

Convert the mixout module to use the module adapter. The
bind/unbind/get_attribute ops in the mixout module have been moved to the
module_adapter ops and is functionally the same as with the comp_drv
ops.

The struct mixout_data struct has been simplified to contain 2 fields as
the source info table has been moved to struct processing_module and
rename the consumed_yet_not_produced_frames field in struct mixout_data
to pending_frames.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>

Author: ranj063