staging: comedi: ni_mio_common.c: fix coding style issue

"checkpatch.pl -f ..." gave
ERROR: open brace '{' following function definitions go on the next line

Signed-off-by: Christopher Mårtensson <cribalik@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>