audio: Set slient persist property according to ringer mode

Update the persist.sys.silent property when setting ringer mode.
This property could be used by the native layer application.
Example:
Bootanimation could check this property to decide whether
background music is needed.

Change-Id: I64311fcac9d4c3729b38fc2b597dc478d6de4d7c
NetworkPolicy: Validate policy templates before updating

Ensure all the policies to be added are validated, otherwise
this service will throw IllegalArgumentException and cause
system crash when updating network template after receiving
ACTION_NETWORK_STATS_UPDATED.

Change-Id: I3faef0ac2a2fcea64ba5dde9c9256f6714280e2e
CRs-Fixed: 561490