audio policy: fix default stream and source effects

Fixed AudioPolicyEffects::addSourceDefaultEffect() and
AudioPolicyEffects::addStreamDefaultEffect() for the case where
not both effect type and uuid are provided.
Use the type and uuid in the descriptor retrieved from the
effect implementation instead of the ones provided as argument when
creating the effect entry.

Test: atest audioeffect_tests:DefaultEffectTest#ManageSourceDefaultEffects
Test: atest audioeffect_tests:DefaultEffectTest#ManageStreamDefaultEffects

Change-Id: Iaf9311967aa0b91c66dd2ff0f136ff744a6642d8