plat/hikey: boot memory layout to dedicated file

Boot memory layout is specific for a platform, but should not be
mixed up with other platform specific attributes. A separate file is
much cleaner and better to compare with other platforms. Take a look
at plat/poplar where it is done the same way.

Moved hikey_def.h to system include folder and moved includes from
hikey_def.h to more general platform_def.h.

Signed-off-by: Michael Brandl <git@fineon.pw>
diff --git a/plat/hisilicon/hikey/aarch64/hikey_helpers.S b/plat/hisilicon/hikey/aarch64/hikey_helpers.S
index 680c0a1..32ff8b4 100644
--- a/plat/hisilicon/hikey/aarch64/hikey_helpers.S
+++ b/plat/hisilicon/hikey/aarch64/hikey_helpers.S
@@ -1,12 +1,12 @@
 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
 #include <arch.h>
 #include <asm_macros.S>
-#include "../hikey_def.h"
+#include <hikey_def.h>
 
 	.globl	plat_my_core_pos
 	.globl	platform_mem_init