ALSA: ctl: change return value in compatibility layer so that it's the same value...

ALSA: ctl: change return value in compatibility layer so that it's the same value in core implementation

In control compatibility layer, when no elements are found by
ELEM_READ/ELEM_WRITE ioctl commands, ENXIO is returned. On the other hand,
in core implementation, ENOENT is returned. This is not good for
ALSA ctl applications.

This commit changes the return value from the compatibility layer so
that the same value is returned.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>