staging: comedi: addi-data: simplify the PCI bar reading

All of the remaining addi-data drivers that use the "common" code
either do not have an eeprom or the PCI controller chip is not a
PLX PCI 9054. Knowing this we can simplify the common code that
reads the PCI bars to get the iobase addresses.

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>