staging: comedi: addi_apci_1564: Remove in-driver watchdog support code

Starting with commit 1496e596 ("staging: comedi: addi_apci_1564: use
addi_watchdog module to init watchdog subdevice"), this driver uses the
addi_watchdog module to provide support for the watchdog subdevice.  Any
remaining watchdog code in-driver can and should be removed.

This will also make future work on the timer and counter subdevices easier.

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>