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/mediatek/mt8173/drivers/mtcmos/mtcmos.h b/plat/mediatek/mt8173/drivers/mtcmos/mtcmos.h
index 6e14e3d..1e58027 100644
--- a/plat/mediatek/mt8173/drivers/mtcmos/mtcmos.h
+++ b/plat/mediatek/mt8173/drivers/mtcmos/mtcmos.h
@@ -3,8 +3,8 @@
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
-#ifndef __MTCMOS_H__
-#define __MTCMOS_H__
+#ifndef MTCMOS_H
+#define MTCMOS_H
 
 /*
  * This function will turn off all the little core's power except cpu 0. The
@@ -15,4 +15,4 @@
 void mtcmos_little_cpu_off(void);
 uint32_t mtcmos_non_cpu_ctrl(uint32_t on, uint32_t mtcmos_num);
 
-#endif /* __MTCMOS_H__ */
+#endif /* MTCMOS_H */