V4L/DVB (8912): cx18: Correct CX23418 PCI configuration settings.

cx18: Correct CX23418 PCI configuration settings.  The CX23418 doesn't have
I/O space registers, so there was no need to try and turn them on (the card
ignores the attempt to set the bit anyway).  Also removed incorrect config
space register setting that was errantly borrowed from ivtv.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>