drivers/elog,pc80: Move cmos_post_log()

Do this to remove elog header dependency from pc80/ and
remove some preprocessor guards.

Change-Id: I98044a28c29a2b1756fb25fb593f505e914a71c0
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38189
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/include/console/console.h

@@ -19,6 +19,7 @@
 void post_code(u8 value);
 void arch_post_code(u8 value);
 void cmos_post_code(u8 value);
+int cmos_post_previous_boot(u8 *code, u32 *extra);
 #if CONFIG(CMOS_POST_EXTRA)
 struct device;
 void post_log_path(const struct device *dev);