staging: comedi: adv_pci_dio: cleanup "disable and clear interrupts" comments

For aesthetics, use a common comment for the switch() that disables and clears
interrupts.

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>