ALSA: firewire-lib: obsolete callbacked member

The member of callbacked in AMDTP stream structure is not used anymore.
Instead, ready_processing member is used to wake up yielding task of user
process.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210524031346.50539-3-o-takashi@sakamocchi.jp


Signed-off-by: Takashi Iwai <tiwai@suse.de>