ALSA: Align the syntax of iov_iter helpers with standard ones

We introduced a couple of helpers for copying iomem over iov_iter, and
the functions were formed like the former copy_from/to_user(), and the
return value was adjusted to 0/-EFAULT, which made the code transition
a bit easier at that time.

OTOH, the standard copy_from/to_iter() functions have different
argument orders and the return value, and this difference can be
confusing.  It's not only confusing but dangerous; actually I did
write a wrong code due to that once :-<

For reducing the confusion, this patch changes the syntax of those
helpers to align with the standard copy_from/to_iter().  The argument
order is changed and the return value is the size of copied bytes.
The callers of those functions are updated accordingly, too.

Link: https://patch.msgid.link/20241230114903.4959-1-tiwai@suse.de


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