ACPI / watchdog: Fix off-by-one error at resource assignment

The resource allocation in WDAT watchdog has off-one-by error, it sets
one byte more than the actual end address.  This may eventually lead
to unexpected resource conflicts.

Fixes: 058dfc76

 (ACPI / watchdog: Add support for WDAT hardware watchdog)
Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>