avrcp/device: Report device connected when abs volume not supported

Notifying the volume interface when the device connected without
absolute volume support. Platform like ChromeOS depends on the device
connected signal to initialize some of the AVRCP functionalities.

Test: atest AvrcpDeviceTest
Test: JBL AVRCP works with CrOS
Bug: 306075444
Change-Id: If81a7d5a0db5352ed27157684d1b094064aefa64