SPM: Shorten 'TFM_GET_CONTAINER_PTR'

Use 'TO_CONTAINER' instead, which is shorter and straight.

Change-Id: I7f669aeed386b34b12ffeb2b9554310dcaa24d55
Signed-off-by: Ken Liu <Ken.Liu@arm.com>
diff --git a/secure_fw/spm/include/utilities.h b/secure_fw/spm/include/utilities.h
index 76c9128..847e406 100644
--- a/secure_fw/spm/include/utilities.h
+++ b/secure_fw/spm/include/utilities.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2020, Arm Limited. All rights reserved.
+ * Copyright (c) 2018-2021, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  *
@@ -30,7 +30,7 @@
 #endif
 
 /* Get container structure start address from member */
-#define TFM_GET_CONTAINER_PTR(ptr, type, member) \
+#define TO_CONTAINER(ptr, type, member) \
     (type *)((unsigned long)(ptr) - offsetof(type, member))
 
 #define ERROR_MSG(msg)