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/rockchip/rk3399/include/shared/m0_param.h b/plat/rockchip/rk3399/include/shared/m0_param.h
index 044e797..a5311c9 100644
--- a/plat/rockchip/rk3399/include/shared/m0_param.h
+++ b/plat/rockchip/rk3399/include/shared/m0_param.h
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef __M0_PARAM_H__
-#define __M0_PARAM_H__
+#ifndef M0_PARAM_H
+#define M0_PARAM_H
 
 #define PARAM_ADDR		0xc0
 
@@ -22,4 +22,4 @@
 #define PARAM_M0_SIZE		0x28
 #define M0_DONE_FLAG		0xf59ec39a
 
-#endif /*__M0_PARAM_H__*/
+#endif /* M0_PARAM_H */