ALSA: fireworks/firewire-lib: Add a quirk for wrong dbs in tx packets

One of Fireworks firmware, named  as 'AudioFire9', seems to transmit
packets with wrong value of dbs. It's always 0x11 but actual size of
data block is different.

This commit adds a flag for this quirk and some codes to calculate
correct size.

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