ALSA: fireworks: fix memory leak of response buffer at error path

After allocating memory object for response buffer, ALSA fireworks
driver has leak of the memory object at error path.

This commit releases the object at the error path.

Fixes: 7d3c1d5('ALSA: fireworks: delayed registration of sound card')
Cc: <stable@vger.kernel.org> # v4.7+
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/fireworks/fireworks.c

@@ -301,6 +301,8 @@ do_registration(struct work_struct *work)
 	snd_efw_transaction_remove_instance(efw);
 	snd_efw_stream_destroy_duplex(efw);
 	snd_card_free(efw->card);
+	kfree(efw->resp_buf);
+	efw->resp_buf = NULL;
 	dev_info(&efw->unit->device,
 		 "Sound card registration failed: %d\n", err);
 }