cpu/intel/car: Prepare for C_ENVIRONMENT_BOOTBLOCK

Pass timestamps and BIST to romstage using the same signature
as C_ENVIRONMENT_BOOTBLOCK will.

Change-Id: Ic90da6b1b5ac3b56c69b593ba447ed8e05c8a4e2
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/30492
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/cpu/intel/romstage.h

@@ -7,8 +7,4 @@ void mainboard_romstage_entry(unsigned long bist);
 
 void platform_enter_postcar(void);
 
-/* romstage_main is called from the cache-as-ram assembly file to prepare
- * CAR stack guards.*/
-asmlinkage void *romstage_main(unsigned long bist);
-
 #endif /* _CPU_INTEL_ROMSTAGE_H */