audio-caf: msm8974: Correctly handle the lack of voice_extn

When building without

AUDIO_FEATURE_ENABLED_MULTI_VOICE_SESSIONS:=true

the voice_extn functions return -ENOSYS when called.  Treat that
return code from the set_parameter functions as success rather
than failing the entire set_parameter sequence.

Prior to this change, adev_set_parameters does nothing when the
voice extensions are not compiled into the code because it
immediately calls voice_set_parameters which then itself immediately
fails due to -ENOSYS being returned from voice_extn_set_parameters.

Change-Id: I5b74f8a94325c26d9f24ba7bd85f5b21b5f1cbdf