ALSA: usb-audio: Avoid potentially repeated XRUN error messages

ALSA: usb-audio: Avoid potentially repeated XRUN error messages

Some XRUN-related error messages may repeat themselves, because there
can be multiple pending packets.  Modify notify_xrun() function to
return whether it's being stopped or not, and show the error message
only once when the XRUN is actually handled.

Along with it, fix a typo of word package to packet in the error
message.

Link: https://patch.msgid.link/20260216141209.1849200-5-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>