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/pc80/mc146818rtc.h

@@ -210,9 +210,6 @@ void cmos_set_checksum(int range_start, int range_end, int cks_loc);
 
 #define CMOS_POST_EXTRA_DEV_PATH  0x01
 
-void cmos_post_log(void);
-#else
-static inline void cmos_post_log(void) {}
 #endif /* CONFIG_CMOS_POST */
 
 #endif /* CONFIG_ARCH_X86 */