ALSA: usb-audio: Convert remaining strlcpy() to strscpy()

USB-audio driver still contains two calls of strlcpy() because the
return size is evaluated.  Basically it just checks whether the string
is copied or not, but since strcpy() may return a negative error code,
we should check the negative value and treat as filled.

Link: https://lore.kernel.org/r/20210115095758.19707-1-tiwai@suse.de


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