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/lib/cpus/aarch64/cortex_a35.h b/include/lib/cpus/aarch64/cortex_a35.h
index ad0fedc..2363198 100644
--- a/include/lib/cpus/aarch64/cortex_a35.h
+++ b/include/lib/cpus/aarch64/cortex_a35.h
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef __CORTEX_A35_H__
-#define __CORTEX_A35_H__
+#ifndef CORTEX_A35_H
+#define CORTEX_A35_H
 
 /* Cortex-A35 Main ID register for revision 0 */
 #define CORTEX_A35_MIDR				0x410FD040
@@ -17,4 +17,4 @@
 #define CORTEX_A35_CPUECTLR_EL1			S3_1_C15_C2_1
 #define CORTEX_A35_CPUECTLR_SMPEN_BIT		(1 << 6)
 
-#endif /* __CORTEX_A35_H__ */
+#endif /* CORTEX_A35_H */