Standardise header guards across codebase

All identifiers, regardless of use, that start with two underscores are
reserved. This means they can't be used in header guards.

The style that this project is now to use the full name of the file in
capital letters followed by 'H'. For example, for a file called
"uart_example.h", the header guard is UART_EXAMPLE_H.

The exceptions are files that are imported from other projects:

- CryptoCell driver
- dt-bindings folders
- zlib headers

Change-Id: I50561bf6c88b491ec440d0c8385c74650f3c106e
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/plat/marvell/a8k/common/mss/mss_pm_ipc.h b/plat/marvell/a8k/common/mss/mss_pm_ipc.h
index 0f69457..1dfa9fa 100644
--- a/plat/marvell/a8k/common/mss/mss_pm_ipc.h
+++ b/plat/marvell/a8k/common/mss/mss_pm_ipc.h
@@ -5,8 +5,8 @@
  * https://spdx.org/licenses
  */
 
-#ifndef __MSS_PM_IPC_H
-#define __MSS_PM_IPC_H
+#ifndef MSS_PM_IPC_H
+#define MSS_PM_IPC_H
 
 #include <mss_ipc_drv.h>
 
@@ -32,4 +32,4 @@
 int mss_pm_ipc_msg_trigger(void);
 
 
-#endif /* __MSS_PM_IPC_H */
+#endif /* MSS_PM_IPC_H */