staging: comedi: addi_apci_1564: use addi_watchdog module to init watchdog subdevice

Use the addi_watchdog module to provide support for the watchdog
subdevice.

Also, rearrange the subdevice init blocks so that the order makes sense.
Digital input/output subdevices and subdevices for DI/DO interrupt
support, followed by timer/counter/watchdog subdevices is the new order.

Signed-off-by: Chase Southwood <chase.southwood@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>