pcmcia/cm4000: fix error code

I'm assuming it's not intended to instantly change the error code
from -ENODEV to -EIO, is it?

Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
Acked-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>