ALSA: fireface: change prototype of handler for async transaction with MIDI messages

In a series of Fireface, devices transfer asynchronous transaction with
MIDI messages. In the transaction, content is different depending on
models. ALSA fireface driver has protocol-dependent handler to pick up
MIDI messages from the content.

In latter models of the series, the transaction is transferred to range
of address sequentially. This seems to check continuity of transferred
messages.

This commit changes prototype of the handler to receive offset of
address for received transactions.

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