ACPI / watchdog: Prefer iTCO_wdt always when WDAT table uses RTC SRAM

After we added quirk for Lenovo Z50-70 it turns out there are at least
two more systems where WDAT table includes instructions accessing RTC
SRAM. Instead of quirking each system separately, look for such
instructions in the table and automatically prefer iTCO_wdt if found.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199033


Reported-by: Arnold Guy <aurnoldg@gmail.com>
Reported-by: Alois Nespor <nespor@fssp.cz>
Reported-by: Yury Pakin <zxwarior@gmail.com>
Reported-by: Ihor Chyhin <ihorchyhin@ukr.net>
Signed-off-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>