btio: Add ifndef/endif guard for btio.h
btio: Add ifndef/endif guard for btio.h

To avoid circular inclusion of include file.

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