Revert "CBMEM: Always have early initialisation"

This reverts commit de1fe7f655.

While things appeared to work, there were actually invalid references
to CAR storage after CAR was torn down on boards without
EARLY_CBMEM_INIT. It was discussed use of CAR_GLOBAL should be
restricted to boards that handle CAR migration properly.

Change-Id: I9969d2ea79c334a7f95a0dbb7c78065720e6ccae
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/3968
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/cpu/x86/Makefile.inc

@@ -1 +1,2 @@
-romstage-$(CONFIG_CACHE_AS_RAM) += car.c
+romstage-$(CONFIG_EARLY_CBMEM_INIT) += car.c
+romstage-$(CONFIG_HAVE_ACPI_RESUME) += car.c