staging: comedi: pcmmio: fix final checkpatch warning

Fis the last checkpatch.pl warning in this driver:

WARNING: space prohibited between function name and open parenthesis '('
+           comedi_buf_put (s->async, val >> 16)) {

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>