tests: Remove unused key policy objects

persistent_key_import() and persistent_key_destroy() don't need to and
don't use key policy objects. Remove unused key policy objects.
diff --git a/tests/suites/test_suite_psa_crypto_persistent_key.function b/tests/suites/test_suite_psa_crypto_persistent_key.function
index 425dabb..753e3d2 100644
--- a/tests/suites/test_suite_psa_crypto_persistent_key.function
+++ b/tests/suites/test_suite_psa_crypto_persistent_key.function
@@ -117,7 +117,6 @@
                              int first_type_arg, data_t *first_data,
                              int second_type_arg, data_t *second_data )
 {
-    psa_key_policy_t policy;
     psa_key_id_t key_id = key_id_arg;
     psa_key_handle_t handle = 0;
     psa_key_type_t first_type = (psa_key_type_t) first_type_arg;
@@ -125,8 +124,6 @@
 
     PSA_ASSERT( psa_crypto_init() );
 
-    psa_key_policy_init( &policy );
-
     PSA_ASSERT( psa_create_key( PSA_KEY_LIFETIME_PERSISTENT, key_id,
                                 first_type,
                                 PSA_BYTES_TO_BITS( first_data->len ),
@@ -171,7 +168,6 @@
 void persistent_key_import( int key_id_arg, int type_arg, data_t *data,
                             int expected_status )
 {
-    psa_key_policy_t policy;
     psa_key_lifetime_t lifetime;
     psa_key_id_t key_id = (psa_key_id_t) key_id_arg;
     psa_key_type_t type = (psa_key_type_t) type_arg;
@@ -183,7 +179,6 @@
                                 type,
                                 PSA_BYTES_TO_BITS( data->len ),
                                 &handle ) );
-    psa_key_policy_init( &policy );
     TEST_EQUAL( psa_import_key( handle, type, data->x, data->len ),
                 expected_status );