Move variant usage to std

Since sdbusplus now uses std, it's cleaner just to
use the variant type directly not behind the namespace.

Also updates clang format.

Style only change.

Tested-by: It builds

Change-Id: I2b7e3ae6b0135cda3e8443e8f910009e6e857f87
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/include/VariantVisitors.hpp b/include/VariantVisitors.hpp
index 4b4adf4..935803e 100644
--- a/include/VariantVisitors.hpp
+++ b/include/VariantVisitors.hpp
@@ -19,56 +19,60 @@
 
 struct VariantToFloatVisitor
 {
-    template <typename T> float operator()(const T &t) const
+    template <typename T>
+    float operator()(const T& t) const
     {
         return static_cast<float>(t);
     }
 };
 template <>
 inline float VariantToFloatVisitor::
-    operator()<std::string>(const std::string &s) const
+    operator()<std::string>(const std::string& s) const
 {
     throw std::invalid_argument("Cannot translate string to float");
 }
 
 struct VariantToIntVisitor
 {
-    template <typename T> int operator()(const T &t) const
+    template <typename T>
+    int operator()(const T& t) const
     {
         return static_cast<int>(t);
     }
 };
 template <>
 inline int VariantToIntVisitor::
-    operator()<std::string>(const std::string &s) const
+    operator()<std::string>(const std::string& s) const
 {
     throw std::invalid_argument("Cannot translate string to int");
 }
 
 struct VariantToUnsignedIntVisitor
 {
-    template <typename T> unsigned int operator()(const T &t) const
+    template <typename T>
+    unsigned int operator()(const T& t) const
     {
         return static_cast<int>(t);
     }
 };
 template <>
 inline unsigned int VariantToUnsignedIntVisitor::
-    operator()<std::string>(const std::string &s) const
+    operator()<std::string>(const std::string& s) const
 {
     throw std::invalid_argument("Cannot translate string to unsigned int");
 }
 
 struct VariantToStringVisitor
 {
-    template <typename T> std::string operator()(const T &t) const
+    template <typename T>
+    std::string operator()(const T& t) const
     {
         return std::to_string(t);
     }
 };
 template <>
 inline std::string VariantToStringVisitor::
-    operator()<std::string>(const std::string &s) const
+    operator()<std::string>(const std::string& s) const
 {
     return s;
 }