monitor: Fix zero-length field handling in print_hex_field
monitor: Fix zero-length field handling in print_hex_field

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