Add check to determine if dinput_mux is set by any of patch_stac*() functions,
otherwise a invalid pointer my be referenced causing gibberish to mixer values.
Signed-off-by: Matthew Ranostay <mranostay@embeddedalley.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
                spec->mixers[spec->num_mixers++] = spec->kctls.list;
 
        spec->input_mux = &spec->private_imux;
-       spec->dinput_mux = &spec->private_dimux;
+       if (!spec->dinput_mux)
+               spec->dinput_mux = &spec->private_dimux;
        spec->sinput_mux = &spec->private_smux;
        spec->mono_mux = &spec->private_mono_mux;
        spec->amp_mux = &spec->private_amp_mux;