ALSA: usb-audio: fixing upper volume limit for RME Babyface Pro routing crosspoints

In my initial patch, these were set too low.

Fixes: 3e8f3bd0

 ("ALSA: usb-audio: RME Babyface Pro mixer patch")
Signed-off-by: Thomas Ebeling <penguins@bollie.de>
Link: https://lore.kernel.org/r/20200515114556.vtspnonzvp4xp44m@bollie.ca9.eu
Signed-off-by: Takashi Iwai <tiwai@suse.de>