Code style fixes for clang-tidy

CI ended up complaining about these in unrelated patches that happened
to touch the same files; rather than clutter up those patches with
completely tangential changes, let's handle them separately.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Change-Id: Ic5bed1d618380e2ebcf33804e11336b6a0a27b1b
diff --git a/src/ExitAirTempSensor.cpp b/src/ExitAirTempSensor.cpp
index 61a03fb..e256bb1 100644
--- a/src/ExitAirTempSensor.cpp
+++ b/src/ExitAirTempSensor.cpp
@@ -595,7 +595,7 @@
         }
         for (const auto& item : subtree)
         {
-            size_t lastSlash = item.first.rfind("/");
+            size_t lastSlash = item.first.rfind('/');
             if (lastSlash == std::string::npos ||
                 lastSlash == item.first.size() || item.second.empty())
             {