ALSA: firewire-digi00x: add skeleton for Digi 002/003 family

This commit adds a new driver for Digidesign 002/003 family. This commit
just creates/removes card instance according to bus event. More functions
will be added in following commits.

Digidesign 002/003 family consists of:
 * Agere FW802B for IEEE 1394 PHY layer
 * PDI 1394L40 for IEEE 1394 LINK layer and IEC 61883 interface
 * ALTERA ACEX EP1K50 for IEC 61883 layer and DSP controller
 * ADSP-21065L for signal processing

[minor cleanup using skip_spaces() by tiwai]

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