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/mainboard/intel/emeraldlake2/Kconfig

@@ -13,6 +13,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	select HAVE_ACPI_RESUME
 	select GFXUMA
 	#select CHROMEOS
+	select EARLY_CBMEM_INIT
 
 config MAINBOARD_DIR
 	string