lib: Add time stamp when starting to finalize chips

Add the new time stamps *finalize chips* to track, when the method
`dev_finalize_chips()` is called, so that the real time of
`write_tables()` is known.

Change-Id: I65ca0ec4c07c2eaa14982989cb206d23d8a2293f
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: https://review.coreboot.org/17725
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)

src/lib/hardwaremain.c

@@ -212,6 +212,7 @@ static boot_state_t bs_write_tables(void *arg)
 	 */
 	write_tables();
 
+	timestamp_add_now(TS_FINALIZE_CHIPS);
 	dev_finalize_chips();
 
 	return BS_PAYLOAD_LOAD;