staging: comedi das08_cs.c: Fix io_req_t conversion

Commit 90abdc3b9 converted all PCMCIA users away from io_req_t. In
das08_cs.c the converted IO lines mask setting was added but the old
line using the now inexistent p_dev->io was not removed.

Signed-off-by: Andreas Bombe <aeb@debian.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>