Condense std::variants

Where possible, reduce to a single std::variant type to reduce binary
size.

Change-Id: I73b59765109ce1ccd7339f0e214d1ec3929e1ffc
Signed-off-by: Jason M. Bills <jason.m.bills@intel.com>
diff --git a/src/sensorcommands.cpp b/src/sensorcommands.cpp
index b8b40e0..0fb04f7 100644
--- a/src/sensorcommands.cpp
+++ b/src/sensorcommands.cpp
@@ -128,8 +128,7 @@
     "type='signal',member='PropertiesChanged',interface='org.freedesktop.DBus."
     "Properties',arg0namespace='xyz.openbmc_project.Sensor.Threshold'",
     [](sdbusplus::message_t& m) {
-        boost::container::flat_map<std::string, std::variant<bool, double>>
-            values;
+        boost::container::flat_map<std::string, ipmi::DbusVariant> values;
         m.read(std::string(), values);
 
         auto findAssert =