ALSA: scarlett2: Fix Direct Monitor control name for 2i2

The Direct Monitor control for the 2i2 is an enumerated value, not a
boolean. Fix the control name to say "Playback Enum" instead of
"Playback Switch" in this case.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/faf5de1d2100038e7d07520d770fda4a1adc276a.1626959758.git.g@b4.vu


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