ALSA: firewire-motu: add support for MOTU 828mk2 as a model with protocol version 2

MOTU 828mk2 is one of second generation in MOTU FireWire series, produced in
2003. This model consists of four chips:
 * TI TSB41AB2 (Physical layer for IEEE 1394 bus)
 * PDI 1394L40BE (Link layer for IEEE 1394 bus and packet processing layer)
 * ALTERA ACEX 1K EP1K30 Series FPGA (Data block processing layer)
 * TI TMS320VC5402 (Digital signal processing)

This commit adds a support for this model, with its unique protocol as
version 2. The features of this protocol are:

 * Support data chunks for status and control messages for both
   directions.
 * Support a pair of MIDI input/output.
 * Support a data chunk for mic/instrument independent of analog line in.
 * Support a data chunk for playback return.
 * Support independent data chunks for S/PDIF of both optical/coaxial
   interfaces.
 * Support independent data chunks for each of main out and phone out.

Status of clock is configured by write transactions to 0x'ffff'f000'0b14.
Modes of optical interfaces are configured by write transactions to
0x'ffff'f000'0c04.

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