hal: support for wide-band speech audio over BT

- Adding support for WB audio with BT devices
- Deprecate bt_samplrate" keyvalue pair which was
  used earlier to determine wide band speech useCase.

Change-Id: Idc766dc4d8ecf25818f16bccc48c6740b0dfce65
diff --git a/hal/audio_hw.h b/hal/audio_hw.h
index a24e95e..d782078 100644
--- a/hal/audio_hw.h
+++ b/hal/audio_hw.h
@@ -269,6 +269,7 @@
     struct voice voice;
     unsigned int cur_hdmi_channels;
     unsigned int cur_wfd_channels;
+    bool bt_wb_speech_enabled;
 
     int snd_card;
     void *platform;