RMX1921: Drop custom APM flag along with no-op audio flags

Custom audio policy manager is hard disabled by CAF
for 2 years now. Remove as well the audio feature flags
that were used to configure it.

Change-Id: Idd34d1cbbdb735d6cf0de3b159c2670bf7ddd1e3
Signed-off-by: kaderbava <ksbava7325@gmail.com>