Use mbedtls_ssl_is_handshake_over()

Switch over to using the new function both internally and in tests.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 855cfc7..65313b9 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -1044,7 +1044,7 @@
     {
         /* If /p second_ssl ends the handshake procedure before /p ssl then
          * there is no need to call the next step */
-        if( second_ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
+        if( !mbedtls_ssl_is_handshake_over( second_ssl ) )
         {
             ret = mbedtls_ssl_handshake_step( second_ssl );
             if( ret != 0 && ret != MBEDTLS_ERR_SSL_WANT_READ &&
@@ -2048,8 +2048,8 @@
         goto exit;
     }
 
-    TEST_ASSERT( client.ssl.state == MBEDTLS_SSL_HANDSHAKE_OVER );
-    TEST_ASSERT( server.ssl.state == MBEDTLS_SSL_HANDSHAKE_OVER );
+    TEST_ASSERT( mbedtls_ssl_is_handshake_over( &client.ssl ) == 1 );
+    TEST_ASSERT( mbedtls_ssl_is_handshake_over( &server.ssl ) == 1 );
 
     /* Check that both sides have negotiated the expected version. */
     mbedtls_test_set_step( 0 );