staging: comedi: drivers: remove unnecessary *_SIZE defines

Some of the legacy comedi drivers have a *_SIZE define that is only
passed to comedi_request_region() to specify the size of the region.

Some of the pnp drivers (pci, etc.) also have a *_SIZE define which
is unused.

For aesthetics, remove these defines.

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>