Fix bitbake error "include nested too deeply"

Remove .hpp to avoid the cyclic include

Change-Id: I4072e34d9503730cd45a96aaca785d2e42e9c3d9
Signed-off-by: Yong Li <yong.b.li@linux.intel.com>
diff --git a/include/filesystem.hpp b/include/filesystem.hpp
index ead619e..9915ee1 100644
--- a/include/filesystem.hpp
+++ b/include/filesystem.hpp
@@ -1,7 +1,7 @@
 // this file splices filesystem in depending on the implementation
 
 #if __has_include(<filesystem>)
-#include <filesystem.hpp>
+#include <filesystem>
 #elif __has_include(<experimental/filesystem>)
 #include <experimental/filesystem>
 namespace std
@@ -11,4 +11,4 @@
 } // namespace std
 #else
 #error filesystem not available
-#endif
\ No newline at end of file
+#endif