utils: simplify getDbusPropertyVariant

Remove the temporary object in order to simplify the code and enable
RVO.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: If7c8c8826e9f080a3e5f8f62537d650c9b54c005
diff --git a/common/utils.cpp b/common/utils.cpp
index 1dd9fdf..2ef0d32 100644
--- a/common/utils.cpp
+++ b/common/utils.cpp
@@ -556,10 +556,7 @@
     auto method = bus.new_method_call(service.c_str(), objPath, dbusProperties,
                                       "Get");
     method.append(dbusInterface, dbusProp);
-    PropertyValue value{};
-    auto reply = bus.call(method, dbusTimeout);
-    reply.read(value);
-    return value;
+    return bus.call(method, dbusTimeout).unpack<PropertyValue>();
 }
 
 PropertyValue jsonEntryToDbusVal(std::string_view type,