ALSA: scarlett2: Split input_other into level/pad/air/phantom

Gen 2/3 devices have a single notification value for "input other"
changes. Gen 4 has separate notification values for level, pad, air,
and phantom power changes. Therefore, split the input_other_updated
field and the scarlett2_update_input_other() function into the four
components so that they can be handled separately later.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/a1a1d190659d56689792aa20ceeb53a6175171ad.1703444932.git.g@b4.vu


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