ALSA: oxfw: fix memory leak for model-dependent data at error path

After allocating model-dependent data, ALSA OXFW driver has memory leak
of the data at error path.

This commit releases the data at the error path.

Fixes: 6c29230e ('ALSA: oxfw: 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/oxfw/oxfw.c

@@ -271,6 +271,8 @@ static void do_registration(struct work_struct *work)
 	if (oxfw->has_output)
 		snd_oxfw_stream_destroy_simplex(oxfw, &oxfw->tx_stream);
 	snd_card_free(oxfw->card);
+	kfree(oxfw->spec);
+	oxfw->spec = NULL;
 	dev_info(&oxfw->unit->device,
 		 "Sound card registration failed: %d\n", err);
 }