staging: comedi: widen subdevice number argument in ioctl handlers

For the `COMEDI_LOCK`, `COMEDI_UNLOCK`, `COMEDI_CANCEL`, and
`COMEDI_POLL` ioctls the third argument is a comedi subdevice number.
This is passed as an `unsigned long`, but when it is passed down to the
ioctl command-specific handler functions `do_lock_ioctl()`,
`do_unlock_ioctl()`, `do_cancel_ioctl()`, and `do_poll_ioctl()`, the
value has been narrowed to an `unsigned int`.  Pass through the argument
as an `unsigned long` to avoid truncating the value on 64-bit
architectures.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>