APM: update the logic of querying dynamic policy with requesting mmap.

1. Do not allow loopback render when mmap is requested. The reason is
   that currently there is no way to identify the request is shared or
   exclusive.
2. Do not allow dynamic policy if the mix device is selected. The reason
   is that AudioPolicyMixCollection is not aware of if the mix device
   supports mmap or not.

Bug: 300121986
Test: atest audiopolicy_tests AudioPlaybackCaptureTest
Test: screen recording when requesting mmap stream
Change-Id: Iae536704f32eebc44bfb824a25d3a6acf2ddb0c8