It's cleared that Fireface 400 transmits quadlet message for two purposes
at least; received MIDI messages and notification of knob control
operation. Nevertheless current implementation uses callback function name
just for MIDI messages.

This commit renames the callback functions.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20230112120954.500692-2-o-takashi@sakamocchi.jpSigned-off-by: Takashi Iwai <tiwai@suse.de>