staging: comedi: pcmmio: remove 'asic' parameter from switch_page()

The board supported by this driver only has one WinSystems WS16C48 asic
on it that handles the digital i/o.

Remove the unnecessary 'asic' parameter that is passed to switch_page().

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>