Fix typos in kossel_pro gcode variable usage
Fix typos in kossel_pro gcode variable usage

Replace double-braces with single-braces so that `material_bed_temperature` and `material_print_temperature` are interpolated properly.
fieldOfView/Cura,fieldOfView/Cura,ynotstartups/Wanhao,Curahelper/Cura,hmflash/Cura,ynotstartups/Wanhao,Curahelper/Cura,hmflash/Cura