Move the definition of data_t to a header file

This way it can be used in helper functions.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/include/test/helpers.h b/tests/include/test/helpers.h
index 787b96a..757a43b 100644
--- a/tests/include/test/helpers.h
+++ b/tests/include/test/helpers.h
@@ -58,6 +58,13 @@
 #include "mbedtls/bignum.h"
 #endif
 
+/** The type of test case arguments that contain binary data. */
+typedef struct data_tag
+{
+    uint8_t *   x;
+    uint32_t    len;
+} data_t;
+
 typedef enum
 {
     MBEDTLS_TEST_RESULT_SUCCESS = 0,
diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 91ad925..a7531e7 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -51,13 +51,6 @@
 #include <strings.h>
 #endif
 
-/* Type for Hex parameters */
-typedef struct data_tag
-{
-    uint8_t *   x;
-    uint32_t    len;
-} data_t;
-
 /*----------------------------------------------------------------------------*/
 /* Status and error constants */