ALSA: bebob: use managed-resource to maintain data specific to M-Audio FW-1814/ProjectMix I/O

ALSA bebob driver allocates memory object for data specific to M-Audio
FW-1884/ProjectMix I/O. The object is to maintain format of isochronous
packet payload for packet streaming by components for ALSA rawMIDI/PCM
interfaces. The object 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>