staging: comedi: amplc_pc236: abbreviate IS_ENABLED()

The IS_ENABLED(CONFIG_COMEDI_AMPLC_PC236_ISA) and
IS_ENABLED(CONFIG_COMEDI_AMPLC_PC236_PCI) macro calls are a bit
long-winded.  Define a couple of macros DO_ISA and DO_PCI as
abbreviations for them.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>