The implicit feedback mode needs to handle two endpoints and the
choice of the audioformat object for the sync EP is important since
this determines the compatibility of the hw_params.  The current code
uses the same audioformat object if both the main EP and the sync EP
point to the same iface/altsetting.  This was done in consideration of
the non-implicit-fb sync EP handling, and it doesn't match well with
the cases where actually to endpoints are defined in the sameiface /
altsetting like a few Pioneer devices.

Modify snd_usb_find_implicit_fb_sync_format() to pick up the
audioformat that is assigned in the counter-part substreams primarily,
so that the actual capture stream can be opened properly.  We keep the
same audioformat object only as a fallback in case nothing found,
though.

Fixes: 9fddc15e ("ALSA: usb-audio: Factor out the implicit feedback quirk code")
Link: https://lore.kernel.org/r/20210108075219.21463-3-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>