hal: bengal: Enable single process of AHAL + AGM

a.This enables audio feature of merging AHAL and AGM
 into single process. Merge agm service into audio hal service
to avoid HwBinder calls between ahal and agm which improves:
  1. MIPS increase due to HwBinder calls
  2. Priority inversion due to binder priority
     restoration

b. Enable audio feature config of merging AHAL and AGM
into single process.

Change-Id: I489c23c287b4aeb04e7d310840ca3c51e17f0b47