usb: gadget: u_audio: Subdevice 0 for capture ctls

Both capture and playback alsa devices use subdevice 0. Yet capture-side
ctls are defined for subdevice 1. The patch sets subdevice 0 for them.

Fixes: 02de698c ("usb: gadget: u_audio: add bi-directional volume and mute support")
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Link: https://lore.kernel.org/r/20220105104643.90125-1-pavel.hofman@ivitera.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>