audio policy: fix regression in Audio MMAP device selection

Commit f3a5a601 caused a regression for AAudio MMAP playback use case
where disconnecting currently selected device does not generate a
disconnect callback to client causing silent audio until the
stream is closed and reopened.

This CL fixes a logical flaw in method SessionRouteMap::getActiveDeviceForStream()
introduced by commit f3a5a601 causing a stale forced device to be
returned after this device was disconnected.

Bug: 111711159
Bug: 79878501
Test: CTS tests for audi routing and AAudio. Audio smoke tests
Merged-In: Ibb16e26bc59b9e3f99bc74eb944601c6be5026dd
Change-Id: Ibb16e26bc59b9e3f99bc74eb944601c6be5026dd