amlogic: Fix header guards

Make the header guards more generic and contextually remove the
GXBB_BL31_PLAT_PARAM_VAL value that is unused on the GXL platform.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Change-Id: I842fa2e084e71280ae17b39c67877e844821a171
diff --git a/plat/amlogic/common/include/aml_private.h b/plat/amlogic/common/include/aml_private.h
index d6629fc..4923745 100644
--- a/plat/amlogic/common/include/aml_private.h
+++ b/plat/amlogic/common/include/aml_private.h
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef GXBB_PRIVATE_H
-#define GXBB_PRIVATE_H
+#ifndef AML_PRIVATE_H
+#define AML_PRIVATE_H
 
 #include <stddef.h>
 #include <stdint.h>
@@ -37,4 +37,4 @@
 uint64_t aml_efuse_read(void *dst, uint32_t offset, uint32_t size);
 uint64_t aml_efuse_user_max(void);
 
-#endif /* GXBB_PRIVATE_H */
+#endif /* AML_PRIVATE_H */