audiopolicy: Fix dump for AudioPolicyMix criterias

The dump code was not using AudioMixMatchCriterion class fields
correctly.

Bug: 112151391
Test: 1. run and pause AudioPolicyTest#testMixByUidCapturing
      2. adb shell dumpsys media.audio_policy

Change-Id: I5f74a0e6dc1a7039eab1470402179b7f9d1cd962