ALSA: firewire-lib: obsolete return value from context payload processing layer

This commit obsoletes return value from the context payload processing layer
since the multiplier between the data block count and PCM frame count was
moved to the packet streaming processing layer.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20230110134933.322794-3-o-takashi@sakamocchi.jp


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