Move testing of mbedtls_blowfish_free() to separate test case

It should be tested regardless of the setting of MBEDTLS_CHECK_PARAMS.
diff --git a/tests/suites/test_suite_blowfish.data b/tests/suites/test_suite_blowfish.data
index e1a614c..fd172d3 100644
--- a/tests/suites/test_suite_blowfish.data
+++ b/tests/suites/test_suite_blowfish.data
@@ -1,4 +1,7 @@
-Blowfish parameter validation
+BLOWFISH - Valid parameters
+blowfish_valid_param:
+
+BLOWFISH - Invalid parameters
 blowfish_invalid_param:
 
 BLOWFISH-ECB Encrypt SSLeay reference #1
diff --git a/tests/suites/test_suite_blowfish.function b/tests/suites/test_suite_blowfish.function
index 1d1422a..7a93cd1 100644
--- a/tests/suites/test_suite_blowfish.function
+++ b/tests/suites/test_suite_blowfish.function
@@ -7,6 +7,13 @@
  * END_DEPENDENCIES
  */
 
+/* BEGIN_CASE */
+void blowfish_valid_param( )
+{
+    TEST_VALID_PARAM( mbedtls_blowfish_free( NULL ) );
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_CHECK_PARAMS:!MBEDTLS_PARAM_FAILED_ALT */
 void blowfish_invalid_param( )
 {