ALSA: fireworks: use managed-resource to maintain response buffer

ALSA fireworks driver allocates memory object to handle response from
target unit. The object is used to initiate transaction unique to
Fireworks board module. This can be released as managed-resource
of 'struct snd_card.card_dev'.

This commit uses managed-resource of the sound card device for this
purpose.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>