staging: comedi: Fix line ending with a (

Fix style issue with declaration by adopting the same style as the
function defintion in drivers/staging/comedi/comedi_buf.c.

Issue reported by checkpatch.

Signed-off-by: John B. Wyatt IV <jbwyatt4@gmail.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Link: https://lore.kernel.org/r/20200329080031.511959-1-jbwyatt4@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>