aaudio: disable exclusive mode after steal

Prevent a process that had its exclusive stream stolen
from obtaining another exclusive stream.
This can prevent a collision between two processes after
they both try to open EXCLUSIVE streams after
a DISCONNECT event.

Bug: 157777324
Test: adb shell test_steal_exclusive -r0 -d100
Change-Id: I0fe12be95a8fbd05ed03f10796e1ca716025c885