staging: comedi: ii_pci20kc: iobase and ioaddr are void __iomem *

The iobase variables in struct pci20xxx_subdev_private and ioaddr
variable in struct pci20xxx_private should be void __iomem * not
void *.

This quiets a lot of sparse warings for the writeb and readb calls
like:

warning: incorrect type in argument 1 (different address spaces)
   expected void const volatile [noderef] <asn:2>*addr
   got void *<noident>

warning: incorrect type in argument 2 (different address spaces)
   expected void volatile [noderef] <asn:2>*addr
   got void *

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Mori Hess <fmhess@users.sourceforge.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>