AVRCP CT: Only call handle_rc_features if target registered

If target is not registered, handle_rc_features would clear feature
flags before handle_rc_ctrl_features can use them.

Bug: b/35807779
Test: AVRCP controller track info works on iOS.
Change-Id: Iee781f2fc926a053ba9cf30089d3a49e56b94539
(cherry picked from commit 7745e29576703a84f4a6b47f13b3cec068033e28)