lpc: Drop __cplusplus guard

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

Change-Id: I7a0979dda90b7968000e05fdf7029dea748a33cc
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/vpnor/lpc_reset.cpp b/vpnor/lpc_reset.cpp
index 6c5a5d6..98fa2be 100644
--- a/vpnor/lpc_reset.cpp
+++ b/vpnor/lpc_reset.cpp
@@ -17,8 +17,11 @@
  *
  */
 
+extern "C" {
 #include "mbox.h"
 #include "lpc.h"
+}
+
 #include "mboxd_pnor_partition_table.h"
 
 /*