staging: comedi: amplc_pci224: add whitespace to pci224_boards[]

Add a bit of whitespace to the initializer of `pci224_boards[]` for
aesthetic reasons.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>