Fix dev num check.

lib/onewire/onewire.c

@@ -241,7 +241,7 @@ uint8_t onewireGetDevicesNum(void) {
 }
 
 int32_t onewireGetTemperature(const size_t num) {
-  if (num > devices_on_bus || num < devices_on_bus) {
+  if ((num+1) > devices_on_bus || (num+1) < devices_on_bus) {
     return -999;
   } else {
     return temperature[num];