staging: comedi: addi_apci_16xx: remove interrupt support code

The boards supported by this driver do not have any interrupt
capable devices. Remove the unused interrupt support code.

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>