staging: comedi: Replace "dont" with "don't

Replace "dont" with "don't".
"Dont" is not same as "Do not" or "Don't".

Signed-off-by: Arushi Singhal <arushisinghal19971997@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>