intel/car: Use common TS_START_ROMSTAGE

This timestamp also got unintentionally removed from some
boards as they were transformed to use common romstage entry.

Change-Id: I12be278a674f9a2ea073b170a223c41c7fc01a94
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34970
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/apollolake/romstage.c

@@ -47,7 +47,6 @@
 #include <soc/systemagent.h>
 #include <spi_flash.h>
 #include <timer.h>
-#include <timestamp.h>
 #include "chip.h"
 
 static const uint8_t hob_variable_guid[16] = {
@@ -199,8 +198,6 @@ void mainboard_romstage_entry(void)
 	struct chipset_power_state *ps = pmc_get_power_state();
 	const void *new_var_data;
 
-	timestamp_add_now(TS_START_ROMSTAGE);
-
 	soc_early_romstage_init();
 
 	s3wake = pmc_fill_power_state(ps) == ACPI_S3;