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/settings.cpp b/settings.cpp
index e8b8997..a51fa95 100644
--- a/settings.cpp
+++ b/settings.cpp
@@ -11,7 +11,6 @@
 
 using namespace phosphor::logging;
 using namespace sdbusplus::xyz::openbmc_project::Common::Error;
-namespace variant_ns = sdbusplus::message::variant_ns;
 
 constexpr auto mapperService = "xyz.openbmc_project.ObjectMapper";
 constexpr auto mapperPath = "/xyz/openbmc_project/object_mapper";
@@ -132,7 +131,7 @@
 
     sdbusplus::message::variant<bool> enabled;
     reply.read(enabled);
-    auto oneTimeEnabled = variant_ns::get<bool>(enabled);
+    auto oneTimeEnabled = std::get<bool>(enabled);
     const Path& setting = oneTimeEnabled ? oneTimeSetting : regularSetting;
     return std::make_tuple(setting, oneTimeEnabled);
 }