staging: comedi: addi_eeprom: rename 'dw_Address'/'w_PCIBoardEepromAddress'

This variable is actually the PCI bar 0 i/o address of the device found
with pci_resource_start().

For aesthetic reasons, rename it to 'iobase' and change to type to an
unsigned long.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>