ALSA: usb-audio: Inform the delayed registration more properly

ALSA: usb-audio: Inform the delayed registration more properly

The info message that was added in the commit a4aad5636c72 ("ALSA:
usb-audio: Inform devices that need delayed registration") is actually
useful to know the need for the delayed registration.  However, it
turned out that this doesn't catch the all cases; namely, this warned
only when a PCM stream is attached onto the existing PCM instance, but
it doesn't count for a newly created PCM instance.  This made
confusion as if there were no further delayed registration.

This patch moves the check to the code path for either adding a stream
or creating a PCM instance.  Also, make it simpler by checking the
card->registered flag instead of querying each snd_device state.

Fixes: a4aad5636c72 ("ALSA: usb-audio: Inform devices that need delayed registration")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216082
Link: https://lore.kernel.org/r/20220831125901.4660-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>