AVRCP: Reject when CT sends invalid RegisterNotification

Check whether the RegisterNotification request from CT is valid, and
safely reject invalid request

Bug: 111260441
Test: manually test with RIVA WAND speaker and run net_test_avrcp
Change-Id: Ia2edd94e50fa7cb5b61be54f297adf971060a924
Merged-In: Ia2edd94e50fa7cb5b61be54f297adf971060a924
(cherry picked from commit db61e462645d2787d5a05f6fa0d0fe9511523c0f)