attrib: Fix sprintf() format specification
attrib: Fix sprintf() format specification

Fixes clang error:

src/attrib-server.c:916:26: error: format specifies type 'unsigned char'
but the argument has type 'uint16_t' (aka 'unsigned short')
[-Werror,-Wformat]

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