remove usage of sdbusplus::message::variant

sdbusplus has had its alias of std::variant in place for long
enough. This changes all ipmid references to use std::variant
directly instead of the sdbusplus alias.

Tested-by: building and running ipmid

Change-Id: Id5b4136d4589aa598815edd3ef4202e64a7698e2
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
diff --git a/user_channel/user_mgmt.cpp b/user_channel/user_mgmt.cpp
index 89ba142..41ec5fa 100644
--- a/user_channel/user_mgmt.cpp
+++ b/user_channel/user_mgmt.cpp
@@ -31,6 +31,7 @@
 #include <regex>
 #include <sdbusplus/bus/match.hpp>
 #include <sdbusplus/server/object.hpp>
+#include <variant>
 #include <xyz/openbmc_project/Common/error.hpp>
 #include <xyz/openbmc_project/User/Common/error.hpp>
 
@@ -106,8 +107,7 @@
 using namespace phosphor::logging;
 using Json = nlohmann::json;
 
-using PrivAndGroupType =
-    sdbusplus::message::variant<std::string, std::vector<std::string>>;
+using PrivAndGroupType = std::variant<std::string, std::vector<std::string>>;
 
 using NoResource =
     sdbusplus::xyz::openbmc_project::User::Common::Error::NoResource;