Staging: comedi: ni_mio_common.c: fixed brace coding style issue in two places

Removed unnecessary braces with the help of  checkpatch.pl tool.

Signed-off-by: Surya Seetharaman <suryaseetharaman.9@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>