Fix memory leak in keymaster unit tests.

Change-Id: Ib5d3b0204c3918f284111f20d2c9ba7b2adf391c
diff --git a/google_keymaster_test.cpp b/google_keymaster_test.cpp
index 837e2ce..ff21f45 100644
--- a/google_keymaster_test.cpp
+++ b/google_keymaster_test.cpp
@@ -374,12 +374,13 @@
 TEST_F(NewKeyGeneration, EcdsaAllValidSizes) {
     size_t valid_sizes[] = {224, 256, 384, 521};
     for (size_t size : valid_sizes) {
+        GenerateKeyResponse rsp;
         req_.key_description.Reinitialize(key_generation_base_params,
                                           array_length(key_generation_base_params));
         req_.key_description.push_back(Authorization(TAG_ALGORITHM, KM_ALGORITHM_ECDSA));
         req_.key_description.push_back(Authorization(TAG_KEY_SIZE, size));
-        device.GenerateKey(req_, &rsp_);
-        EXPECT_EQ(KM_ERROR_OK, rsp_.error) << "Failed to generate size: " << size;
+        device.GenerateKey(req_, &rsp);
+        EXPECT_EQ(KM_ERROR_OK, rsp.error) << "Failed to generate size: " << size;
     }
 }