binaryPI: Clean leftover romstage prototype

Change-Id: Ie9e7a88f1f8dce967772e7c5ecf4aea971bb1c3f
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37346
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/cpu/amd/car.h

@@ -3,8 +3,6 @@
 
 #include <arch/cpu.h>
 
-void cache_as_ram_main(unsigned long bist, unsigned long cpu_init_detectedx);
-
 void *asmlinkage romstage_main(unsigned long bist);
 
 #endif