Ignore readings of "85" in MeterW1therm.cpp

DS18x20 sensors seem to report the default value of "85" every now and again.
These readings are wrong and should be ignored.

src/protocols/MeterW1therm.cpp

@@ -76,8 +76,12 @@ bool MeterW1therm::W1sysHWif::readTemp(const std::string &device, double &value)
 				if (pos) {
 					pos += 2;
 					value = atof(pos)/1000;
-					toret = true;
-					print(log_finest, "read %f from %s (%s)", "w1t", value, dev.c_str(), pos-2);
+					if (value == "85") {
+					  print(log_debug, "Read default value of 85 from %s, ignoring", "w1t", dev.c_str(), pos-2);
+					} else {
+						toret = true;
+						print(log_finest, "read %f from %s (%s)", "w1t", value, dev.c_str(), pos-2);
+					}
 				}
 			} else {
 				print(log_debug, "couldn't read 2nd line from %s", "w1t", dev.c_str());