ALSA: dice: use structure to represent register parameters instead of array with basic type element

In dice interface, two blocks of register are accessible via IEEE 1394
asynchronous transaction to represent the number of supported isochronous
streams and the number of quadlets for stream information.

Current ALSA dice driver uses array with 'unsigned int' element for
temporary cache of these information. But using structure is preferable
for begin easily comprehensible.

This commit applies a local structure for this aim.

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