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/pmu_regs.h b/plat/rockchip/rk3399/include/shared/pmu_regs.h
index 41c6a24..43e785e 100644
--- a/plat/rockchip/rk3399/include/shared/pmu_regs.h
+++ b/plat/rockchip/rk3399/include/shared/pmu_regs.h
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef __PMU_REGS_H__
-#define __PMU_REGS_H__
+#ifndef PMU_REGS_H
+#define PMU_REGS_H
 
 #define PMU_WKUP_CFG0		0x00
 #define PMU_WKUP_CFG1		0x04
@@ -145,4 +145,4 @@
 #define GRF_GPIO4C_P		0xe068
 #define GRF_GPIO4D_P		0xe06C
 
-#endif /* __PMU_REGS_H__ */
+#endif /* PMU_REGS_H */