Enable cppcoreguidelines-pro-type-vararg check

We only had one usage of printf in the code that was in violation of
this rule, so replace it with iostreams, and enable the check.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Ie62165b599a996f34893aa5a3f8d1f6e6cbaf903
diff --git a/src/HwmonTempSensor.cpp b/src/HwmonTempSensor.cpp
index 09fb33f..6577739 100644
--- a/src/HwmonTempSensor.cpp
+++ b/src/HwmonTempSensor.cpp
@@ -52,11 +52,20 @@
            false, thisSensorParameters.maxValue, thisSensorParameters.minValue,
            conn, powerState),
     std::enable_shared_from_this<HwmonTempSensor>(), objServer(objectServer),
-    inputDev(io, open(path.c_str(), O_RDONLY)), waitTimer(io), path(path),
+    inputDev(io), waitTimer(io), path(path),
     offsetValue(thisSensorParameters.offsetValue),
     scaleValue(thisSensorParameters.scaleValue),
     sensorPollMs(static_cast<unsigned int>(pollRate * 1000))
 {
+    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)
+    int fd = open(path.c_str(), O_RDONLY);
+    if (fd < 0)
+    {
+        std::cerr << "HwmonTempSensor " << sensorName << " failed to open "
+                  << path << "\n";
+    }
+    inputDev.assign(fd);
+
     sensorInterface = objectServer.add_interface(
         "/xyz/openbmc_project/sensors/" + thisSensorParameters.typeName + "/" +
             name,
@@ -164,6 +173,8 @@
 
     responseStream.clear();
     inputDev.close();
+
+    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg)
     int fd = open(path.c_str(), O_RDONLY);
     if (fd < 0)
     {