AVRCP: use a vtable to simplify PDU parsing/handling
AVRCP: use a vtable to simplify PDU parsing/handling

This simplify a bit the handling by introducing common checks before
calling the handler callback, it is also much easier to add/remove
new PDUs in this way.

mapfau/bluez,ComputeCycles/bluez,silent-snowman/bluez,silent-snowman/bluez,pkarasev3/bluez,mapfau/bluez,pkarasev3/bluez,pkarasev3/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,mapfau/bluez,ComputeCycles/bluez,silent-snowman/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,pstglia/external-bluetooth-bluez