ALSA: usb-audio: scarlett2: Fix scarlett2_*_ctl_put() return values

Mixer control put callbacks should return 1 if the value is changed.
Fix the sw_hw, level, pad, and button controls accordingly.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/20210620164645.GA9221@m.b4.vu


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