mainboard/*: Convert to generic ITE superio romstage component

Convert mainboard's that use model specific romstage functions of
it8712f to the generic framework by following the reasoning of:

a7d14a1 ite/common: Introduce common watchdog and 3.3V VSB helpers

Change-Id: I1485306a951103c9a4bc0dbe87c416c91f46c36f
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/5737
Tested-by: build bot (Jenkins)
Reviewed-by: Idwer Vollering <vidwer@gmail.com>
Reviewed-by: Marc Jones <marc.jones@se-eng.com>