tests: Get rid of mbedtls_test_unhexify() in unit test code

In test functions calling mbedtls_test_unhexify(), change the
type of the associated parameters from `char*` to `data_t`.

That way the `unhexify` operation is done by the test
framework and not by the unit test code.

Use for the new parameters of type data_t the name of the
local variable that used to store the `unhexify` version of
the `char*` parameter.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/suites/test_suite_ecdh.function b/tests/suites/test_suite_ecdh.function
index 640dc76..32d41e6 100644
--- a/tests/suites/test_suite_ecdh.function
+++ b/tests/suites/test_suite_ecdh.function
@@ -340,7 +340,7 @@
 /* END_CASE */
 
 /* BEGIN_CASE depends_on:MBEDTLS_ECP_RESTARTABLE */
-void ecdh_restart( int id, char *dA_str, char *dB_str, char *z_str,
+void ecdh_restart( int id, data_t *dA, data_t *dB, data_t *z,
                    int enable, int max_ops, int min_restart, int max_restart )
 {
     int ret;
@@ -348,10 +348,6 @@
     unsigned char buf[1000];
     const unsigned char *vbuf;
     size_t len;
-    unsigned char z[MBEDTLS_ECP_MAX_BYTES];
-    size_t z_len;
-    unsigned char rnd_buf_A[MBEDTLS_ECP_MAX_BYTES];
-    unsigned char rnd_buf_B[MBEDTLS_ECP_MAX_BYTES];
     rnd_buf_info rnd_info_A, rnd_info_B;
     int cnt_restart;
     mbedtls_ecp_group grp;
@@ -360,13 +356,11 @@
     mbedtls_ecdh_init( &srv );
     mbedtls_ecdh_init( &cli );
 
-    z_len = mbedtls_test_unhexify( z, z_str );
+    rnd_info_A.buf = dA->x;
+    rnd_info_A.length = dA->len;
 
-    rnd_info_A.buf = rnd_buf_A;
-    rnd_info_A.length = mbedtls_test_unhexify( rnd_buf_A, dA_str );
-
-    rnd_info_B.buf = rnd_buf_B;
-    rnd_info_B.length = mbedtls_test_unhexify( rnd_buf_B, dB_str );
+    rnd_info_B.buf = dB->x;
+    rnd_info_B.length = dB->len;
 
     /* The ECDH context is not guaranteed ot have an mbedtls_ecp_group structure
      * in every configuration, therefore we load it separately. */
@@ -436,8 +430,8 @@
     TEST_ASSERT( cnt_restart >= min_restart );
     TEST_ASSERT( cnt_restart <= max_restart );
 
-    TEST_ASSERT( len == z_len );
-    TEST_ASSERT( memcmp( buf, z, len ) == 0 );
+    TEST_ASSERT( len == z->len );
+    TEST_ASSERT( memcmp( buf, z->x, len ) == 0 );
 
     /* client computes shared secret */
     memset( buf, 0, sizeof( buf ) );
@@ -453,8 +447,8 @@
     TEST_ASSERT( cnt_restart >= min_restart );
     TEST_ASSERT( cnt_restart <= max_restart );
 
-    TEST_ASSERT( len == z_len );
-    TEST_ASSERT( memcmp( buf, z, len ) == 0 );
+    TEST_ASSERT( len == z->len );
+    TEST_ASSERT( memcmp( buf, z->x, len ) == 0 );
 
 exit:
     mbedtls_ecp_group_free( &grp );