Replace include guards with #pragma once

Change-Id: I16adc78d397e3239440206e8e70ebbd5e0963adb
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/sysfs.hpp b/sysfs.hpp
index 7943211..3a51a29 100644
--- a/sysfs.hpp
+++ b/sysfs.hpp
@@ -1,5 +1,4 @@
-#ifndef __SYSFS_H
-#define __SYSFS_H
+#pragma once
 
 #include <fstream>
 #include <string>
@@ -28,6 +27,4 @@
     return path + "/"s + type + id + "_"s + entry;
 }
 
-#endif
-
 // vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4