Replace std::experimental::filesystem with std::filesystem

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I91d2f1b7a8858ba8c676b68693863bb35b56dffc
diff --git a/occ_device.hpp b/occ_device.hpp
index 4215640..a877c8c 100644
--- a/occ_device.hpp
+++ b/occ_device.hpp
@@ -8,7 +8,7 @@
 
 #include <org/open_power/OCC/Device/error.hpp>
 
-#include <experimental/filesystem>
+#include <filesystem>
 #include <fstream>
 
 namespace open_power
@@ -18,7 +18,7 @@
 
 class Manager;
 class Status;
-namespace fs = std::experimental::filesystem;
+namespace fs = std::filesystem;
 using namespace sdbusplus::org::open_power::OCC::Device::Error;
 
 /** @class Device