flash: Drop __cplusplus guard

C++ concepts should go in C++ files.

Change-Id: I7d3b16c4d176b51fb8bcf976744312632322c2a8
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/vpnor/flash.cpp b/vpnor/flash.cpp
index 3d512cb..2d58463 100644
--- a/vpnor/flash.cpp
+++ b/vpnor/flash.cpp
@@ -12,10 +12,10 @@
 
 extern "C" {
 #include "common.h"
+#include "flash.h"
 }
 
 #include "config.h"
-#include "flash.h"
 #include "mboxd_pnor_partition_table.h"
 #include "pnor_partition.hpp"
 #include "pnor_partition_table.hpp"