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/marvell/common/mss/mss_scp_bootloader.h b/plat/marvell/common/mss/mss_scp_bootloader.h
index 67c387a..4950d24 100644
--- a/plat/marvell/common/mss/mss_scp_bootloader.h
+++ b/plat/marvell/common/mss/mss_scp_bootloader.h
@@ -5,8 +5,8 @@
  * https://spdx.org/licenses
  */
 
-#ifndef __MSS_SCP_BOOTLOADER_H__
-#define __MSS_SCP_BOOTLOADER_H__
+#ifndef MSS_SCP_BOOTLOADER_H
+#define MSS_SCP_BOOTLOADER_H
 
 int scp_bootloader_transfer(void *image, unsigned int image_size);
 uintptr_t bl2_plat_get_cp_mss_regs(int ap_idx, int cp_idx);
@@ -16,4 +16,4 @@
 void bl2_plat_configure_mss_windows(uintptr_t mss_regs);
 int bl2_plat_mss_check_image_ready(void);
 
-#endif /* __MSS_SCP_BOOTLOADER_H__ */
+#endif /* MSS_SCP_BOOTLOADER_H */