hal: Add support for scrambler and backend configuration

- Check for scrambler support with BT IPC lib and
  enable scrambler.
- Add support to configure backend with multiple sampling rates
  and different channels over a2dp path.
- Removed "AFE Input Channels" mixer control in order to avoid
  overriding of value set from userspace in kernel

Change-Id: I2324d4867f8f8a498768a41f4db04e138cc26e21