staging: comedi: addi_apci_3120: rename private data 'i_IobaseAmcc'

This member of the private data holds the start address of PCI BAR 0 that is
used to access the AMCC registers.

Rename this CamelCase member and fix its type.

Remove an unnecessary local variable, 'ui_Tmp', in apci3120_cyclic_ai() and
tidy up the rest of the local variable declarations.

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>