staging: comedi: rtd520: use pci_ioremap_bar()

Use pci_ioremap_bar() to ioremap the PCI bars used by this driver.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>