Audio Policy: Engine Configurable: Force Encoded surround setting

This patch is the counter part of 09bc4612.
It solves Bug: 26373761 for configurable policy engine, i.e. Parameter-framework
based policy.

Bug: 26373761

Change-Id: I5f01732238375c1fa08a8f2116698d4362840ba6
Signed-off-by: François Gaffie <francois.gaffie@intel.com>