hal: Add audio hal plugin for external codec

Add audio hal plugin for external codec support so that OEM can add
their own codec implementation.

Change-Id: I67f6808c41c5d9d85d9b6a6a8b49a4f9fd042ab0
Merge "hal: Add audio hal plugin for external codec"
hal: Update audio hw plugin enabling calling sequence

Update the audio hw plugin enabling in audio HAL so
the proper parameters by the external codec can be passed
down to external codec driver.

Change-Id: I01d3f46bc08466d9c83711b3ec112745ef67c3f2
hal: Update audio HAL to enable the hw plugin APIs

Update the audio HAL to enable the hw plugin APIs so
that the external codec can be properly configured.

Change-Id: Iceb19cbadd2f6cb443b8686643da668b1378e87e
Merge "hal: Update audio hw plugin enabling calling sequence"
Merge "hal: Update audio HAL to enable the hw plugin APIs"