AVRCP: Change notification variable when the interim response is sent
This avoids the possibility of having a changed notification be sent
before an interim response is sent when the AVRCP service has to wait
for a response from the media layer for information regarding the
notification.
Also fix the PlayPosition test for AVRCP as it was testing for play
state correctness.
Bug:
109588762
Test: Run host test net_test_avrcp
Change-Id: Icb7bb1068191ecf2a2e390854084b6b9b47537fa
(cherry picked from commit
2d87908fe8825245dcc2e1dbde027331f1e2371d)