staging: comedi: mf6x4: remove unnecassary masking of digital outputs

THe 's->state' will always be in range for the 8 digital outputs.
Remove the unnecessary masking of the value.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
 drivers/staging/comedi/drivers/mf6x4.c | 6 +++---
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>