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/drivers/auth/mbedtls/mbedtls_common.h b/include/drivers/auth/mbedtls/mbedtls_common.h
index 5d3e198..a9c2352 100644
--- a/include/drivers/auth/mbedtls/mbedtls_common.h
+++ b/include/drivers/auth/mbedtls/mbedtls_common.h
@@ -4,9 +4,9 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef __MBEDTLS_COMMON_H__
-#define __MBEDTLS_COMMON_H__
+#ifndef MBEDTLS_COMMON_H
+#define MBEDTLS_COMMON_H
 
 void mbedtls_init(void);
 
-#endif /* __MBEDTLS_COMMON_H__ */
+#endif /* MBEDTLS_COMMON_H */
diff --git a/include/drivers/auth/mbedtls/mbedtls_config.h b/include/drivers/auth/mbedtls/mbedtls_config.h
index cc57b77..d143d73 100644
--- a/include/drivers/auth/mbedtls/mbedtls_config.h
+++ b/include/drivers/auth/mbedtls/mbedtls_config.h
@@ -3,8 +3,8 @@
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
-#ifndef __MBEDTLS_CONFIG_H__
-#define __MBEDTLS_CONFIG_H__
+#ifndef MBEDTLS_CONFIG_H
+#define MBEDTLS_CONFIG_H
 
 /*
  * Key algorithms currently supported on mbed TLS libraries
@@ -104,4 +104,4 @@
 #define TF_MBEDTLS_HEAP_SIZE		U(7168)
 #endif
 
-#endif /* __MBEDTLS_CONFIG_H__ */
+#endif /* MBEDTLS_CONFIG_H */