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/services/spd/trusty/smcall.h b/services/spd/trusty/smcall.h
index 99f1608..742c8c4 100644
--- a/services/spd/trusty/smcall.h
+++ b/services/spd/trusty/smcall.h
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef __LIB_SM_SMCALL_H
-#define __LIB_SM_SMCALL_H
+#ifndef SMCALL_H
+#define SMCALL_H
 
 #define SMC_NUM_ENTITIES	64
 #define SMC_NUM_ARGS		4
@@ -72,4 +72,4 @@
 #define SMC_YC_VDEV_KICK_VQ	  SMC_YIELDCALL_NR(SMC_ENTITY_TRUSTED_OS, 24)
 #define SMC_YC_SET_ROT_PARAMS	  SMC_YIELDCALL_NR(SMC_ENTITY_TRUSTED_OS, 65535)
 
-#endif /* __LIB_SM_SMCALL_H */
+#endif /* SMCALL_H */