lpc: Rename header-guard

Make it align with the file name.

Change-Id: I82cad8c09dffffc479af600822c2ccd2af8d0f7a
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/lpc.h b/lpc.h
index bd3e2b1..9a27677 100644
--- a/lpc.h
+++ b/lpc.h
@@ -1,8 +1,8 @@
 /* SPDX-License-Identifier: Apache-2.0 */
 /* Copyright (C) 2018 IBM Corp. */
 
-#ifndef MBOXD_LPC_H
-#define MBOXD_LPC_H
+#ifndef LPC_H
+#define LPC_H
 
 #ifdef __cplusplus
 extern "C" {
@@ -18,4 +18,4 @@
 }
 #endif
 
-#endif /* MBOXD_LPC_H */
+#endif /* LPC_H */