ALSA: usb-audio: Avoid unnecessary or invalid connector selection at resume

The recent fix for the resume on Lenovo machines seems causing a
regression on others.  It's because the change always triggers the
connector selection no matter which widget node type is.

This patch addresses the regression by setting the resume callback
selectively only for the connector widget.

Fixes: 44609fc0 ("ALSA: usb-audio: Check connector value on resume")
Cc: <stable@vger.kernel.org>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=213897
Link: https://lore.kernel.org/r/20210729185126.24432-1-tiwai@suse.de


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