Floss: Empower avrcp to be toggled by admin

It is locally verified that b/251692015 no longer happens. Make AVRCP as
toggleable by BluetoothAdmin as other media profiles.

Bug: 251692015
Test: Disable AVRCP and connect with WF-1000XM3. Verify there is no
crash.

Change-Id: I08fb97d214f27e8d90d99ee6e7d1e4fae9ea1822