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/ti/k3/include/k3_gicv3.h b/plat/ti/k3/include/k3_gicv3.h
index bbf5bf9..52f34ff 100644
--- a/plat/ti/k3/include/k3_gicv3.h
+++ b/plat/ti/k3/include/k3_gicv3.h
@@ -4,8 +4,10 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef __K3_GICV3_H__
-#define __K3_GICV3_H__
+#ifndef K3_GICV3_H
+#define K3_GICV3_H
+
+#include <stdint.h>
 
 void k3_gic_driver_init(uintptr_t gicd_base, uintptr_t gicr_base);
 void k3_gic_init(void);
@@ -13,4 +15,4 @@
 void k3_gic_cpuif_disable(void);
 void k3_gic_pcpu_init(void);
 
-#endif /* __K3_GICV3_H__ */
+#endif /* K3_GICV3_H */