intel/cpu: rename car.h to romstage.h

This header has nothing to do with cache-as-ram. Therefore, 'car'
is the wrong term to use. It is about providing a prototype for
*romstage*.

Change-Id: Ibc5bc6f3c38e74d6337c12f246846853ceae4743
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/6661
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/mainboard/emulation/qemu-i440fx/romstage.c

@@ -33,7 +33,7 @@
 
 #include "memory.c"
 
-#include <cpu/intel/car.h>
+#include <cpu/intel/romstage.h>
 void main(unsigned long bist)
 {
 	int cbmem_was_initted;

src/mainboard/emulation/qemu-q35/romstage.c

@@ -34,7 +34,7 @@
 
 #include "../qemu-i440fx/memory.c"
 
-#include <cpu/intel/car.h>
+#include <cpu/intel/romstage.h>
 void main(unsigned long bist)
 {
 	int cbmem_was_initted;