staging: comedi: ni_mio_common: checkpatch.pl cleanup (braces not necessary)

Fix the checkpatch.pl warnings:

WARNING: braces {} are not necessary for single statement blocks
WARNING: braces {} are not necessary for any arm of this statement

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