staging: comedi: ni_mio_common: checkpatch.pl cleanup (break not useful)

Fix the checkpatch.pl warning:

WARNING: break is not useful after a goto or return

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>