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/include/bl32/tsp/platform_tsp.h b/include/bl32/tsp/platform_tsp.h
index a5a0223..fe8a2c9 100644
--- a/include/bl32/tsp/platform_tsp.h
+++ b/include/bl32/tsp/platform_tsp.h
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef __PLATFORM_TSP_H__
-
+#ifndef PLATFORM_TSP_H
+#define PLATFORM_TSP_H
 
 /*******************************************************************************
  * Mandatory TSP functions (only if platform contains a TSP)
@@ -14,7 +14,4 @@
 void tsp_plat_arch_setup(void);
 void tsp_platform_setup(void);
 
-
-#define __PLATFORM_H__
-
-#endif
+#endif /* PLATFORM_TSP_H */