audio: Update hal to handle 32bit/384kHz playback.

Update the mixer control string used to configure BE at 32bit format
with correct value.
For HDMI backend, as it does not support 32bit/384kHz, configure
BE to 24bit/192kHz if supported by the connected device.
Configure speaker device to bit width supported on the device
if stream bit width is greater than 24 bit.

Change-Id: Ic1c437d4cb15db709941eec065d40b2ae173ea9d