Audio policy config: remove cross-module device port name uniqueness

This constraint was added due to an incorrect assumption
that device ports were identified by names whereas
they are by the (module,type,address) triplet.

Bug: 69442986
Test: xmllint validates an XML with two identically named devices in
      different modules.
Test: vts-tradefed run commandAndExit vts --module VtsHalAudioV2_0Target -t CheckConfig.audioPolicyConfigurationValidation
Change-Id: I66d890d3c967bead4f2a287202c259009217996a
Signed-off-by: Kevin Rocard <krocard@google.com>