drivers: staging: comedi: fixed duplicate words from checkpatch

Fixed various different checkpatch duplicate word warnings, the TODO
file said to fix checkpatch warnings.

Signed-off-by: Ethan Edwards <ethancarteredwards@gmail.com>
Link: https://lore.kernel.org/r/20200825002955.e3wvtwsoqqbc2cvl@archlaptop.localdomain
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>