Platform: Update the include statements

Change the absolute including into relative path including
for platform sources.

Change-Id: I594577eae7689ea8ac6cb557d5b0b5a048ee9b4d
Signed-off-by: Mingyang Sun <mingyang.sun@arm.com>
diff --git a/platform/ext/common/template/crypto_keys.c b/platform/ext/common/template/crypto_keys.c
index fde597d..c5564e5 100644
--- a/platform/ext/common/template/crypto_keys.c
+++ b/platform/ext/common/template/crypto_keys.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2019 Arm Limited. All rights reserved.
+ * Copyright (c) 2017-2020 Arm Limited. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#include "platform/include/tfm_plat_crypto_keys.h"
+#include "tfm_plat_crypto_keys.h"
 #include <stddef.h>
 #include "psa/crypto_types.h"