Refactor PropertiesChanged handler setup

Most sensor daemons had pretty much the same duplicated open-coded
pattern for setting up PropertiesChanged signal matches; introduce a
helper function to reduce the duplication and make things more readable.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Change-Id: I803a21eea2f6d7fc71b50d54bb8fd57a104f3349
diff --git a/src/FanMain.cpp b/src/FanMain.cpp
index 13902c7..87e27c6 100644
--- a/src/FanMain.cpp
+++ b/src/FanMain.cpp
@@ -525,7 +525,6 @@
         tachSensors;
     boost::container::flat_map<std::string, std::unique_ptr<PwmSensor>>
         pwmSensors;
-    std::vector<std::unique_ptr<sdbusplus::bus::match_t>> matches;
     auto sensorsChanged =
         std::make_shared<boost::container::flat_set<std::string>>();
 
@@ -562,15 +561,8 @@
         });
     };
 
-    for (const char* type : sensorTypes)
-    {
-        auto match = std::make_unique<sdbusplus::bus::match_t>(
-            static_cast<sdbusplus::bus_t&>(*systemBus),
-            "type='signal',member='PropertiesChanged',path_namespace='" +
-                std::string(inventoryPath) + "',arg0namespace='" + type + "'",
-            eventHandler);
-        matches.emplace_back(std::move(match));
-    }
+    std::vector<std::unique_ptr<sdbusplus::bus::match_t>> matches =
+        setupPropertiesChangedMatches(*systemBus, sensorTypes, eventHandler);
 
     // redundancy sensor
     std::function<void(sdbusplus::message_t&)> redundancyHandler =