watchdog: ebc-c384_wdt: Utilize the ISA bus driver

The WinSystems EBC-C384 watchdog timer is controlled via ISA bus
communication. As such, the ISA bus driver is more appropriate than the
platform driver for the WinSystems EBC-C384 watchdog timer driver.

Cc: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>