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_common.c b/plat/hisilicon/hikey/aarch64/hikey_common.c
index f95af58..658760b 100644
--- a/plat/hisilicon/hikey/aarch64/hikey_common.c
+++ b/plat/hisilicon/hikey/aarch64/hikey_common.c
@@ -9,13 +9,12 @@
 #include <assert.h>
 #include <bl_common.h>
 #include <debug.h>
+#include <hikey_def.h>
+#include <hikey_layout.h>
 #include <mmio.h>
 #include <platform.h>
-#include <platform_def.h>
 #include <xlat_tables.h>
 
-#include "../hikey_def.h"
-
 #define MAP_DDR		MAP_REGION_FLAT(DDR_BASE,			\
 					DDR_SIZE - DDR_SEC_SIZE,	\
 					MT_DEVICE | MT_RW | MT_NS)