Unify to use ARRAY_SIZE in TF-M codes

ARRAY_SIZE(foo) is preferred over sizeof(foo)/sizeof(foo[0]).

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I6d95ceece2edc6267491923e282e28710b68ab8d
diff --git a/interface/src/tfm_firmware_update_func_api.c b/interface/src/tfm_firmware_update_func_api.c
index b8d3541..1d34d03 100644
--- a/interface/src/tfm_firmware_update_func_api.c
+++ b/interface/src/tfm_firmware_update_func_api.c
@@ -5,14 +5,12 @@
  *
  */
 
+#include "psa/client.h"
 #include "psa/update.h"
 #include "tfm_api.h"
-
 #include "tfm_ns_interface.h"
 #include "tfm_veneers.h"
 
-#define IOVEC_LEN(x) (uint32_t)(sizeof(x)/sizeof(x[0]))
-
 psa_status_t psa_fwu_write(uint32_t image_id,
                            size_t block_offset,
                            const void *block,