watchdog: pcwd: Utilize the module_isa_driver macro

This driver does not do anything special in module init/exit. This patch
eliminates the module init/exit boilerplate code by utilizing the
module_isa_driver macro.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>