drivers/pc80/rtc: Separate {get|set}_option() prototypes

Long-term plan is to support loading runtime configuration
from SPI flash as an alternative, so move these prototypes
outside pc80/.

Change-Id: Iad7b03dc985550da903d56b3deb5bd736013f8f1
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38192
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/superio/ite/it8720f/superio.c

@@ -18,7 +18,7 @@
 #include <device/device.h>
 #include <device/pnp.h>
 #include <pc80/keyboard.h>
-#include <pc80/mc146818rtc.h>
+#include <option.h>
 #include <superio/ite/common/env_ctrl.h>
 #include <superio/conf_mode.h>
 #include <types.h>