move variant to std namespace

sdbusplus::message::variant_ns has been std for a while now. This moves
ipmid away from sdbusplus::message::variant_ns to directly use
std::variant.

Tested-by: built, compiles, and runs the same as before.

Change-Id: I8caa945f31c926c2721319f001b9d7f83fd3f1b7
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
diff --git a/sensorhandler.cpp b/sensorhandler.cpp
index 48546af..4c0fe01 100644
--- a/sensorhandler.cpp
+++ b/sensorhandler.cpp
@@ -32,8 +32,6 @@
 using InternalFailure =
     sdbusplus::xyz::openbmc_project::Common::Error::InternalFailure;
 
-namespace variant_ns = sdbusplus::message::variant_ns;
-
 void register_netfn_sen_functions() __attribute__((constructor));
 
 struct sensorTypemap_t
@@ -443,10 +441,10 @@
     auto warnThresholds = ipmi::getAllDbusProperties(
         bus, service, info.sensorPath, warningThreshIntf);
 
-    double warnLow = variant_ns::visit(ipmi::VariantToDoubleVisitor(),
-                                       warnThresholds["WarningLow"]);
-    double warnHigh = variant_ns::visit(ipmi::VariantToDoubleVisitor(),
-                                        warnThresholds["WarningHigh"]);
+    double warnLow = std::visit(ipmi::VariantToDoubleVisitor(),
+                                warnThresholds["WarningLow"]);
+    double warnHigh = std::visit(ipmi::VariantToDoubleVisitor(),
+                                 warnThresholds["WarningHigh"]);
 
     if (warnLow != 0)
     {
@@ -468,10 +466,10 @@
 
     auto critThresholds = ipmi::getAllDbusProperties(
         bus, service, info.sensorPath, criticalThreshIntf);
-    double critLow = variant_ns::visit(ipmi::VariantToDoubleVisitor(),
-                                       critThresholds["CriticalLow"]);
-    double critHigh = variant_ns::visit(ipmi::VariantToDoubleVisitor(),
-                                        critThresholds["CriticalHigh"]);
+    double critLow = std::visit(ipmi::VariantToDoubleVisitor(),
+                                critThresholds["CriticalLow"]);
+    double critHigh = std::visit(ipmi::VariantToDoubleVisitor(),
+                                 critThresholds["CriticalHigh"]);
 
     if (critLow != 0)
     {