staging: comedi: change bool assignment to true

This is a minor fix that was suggested by coccinelle. When defined as a
bool, a variable should use true/false rather than 1/0.

Signed-off-by: Teodora Baluta <teobaluta@gmail.com>
Reviewed-by: Lisa Nguyen <lisa@xenapiadmin.com>
Reviewed-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>