CBMEM: Tag chipsets with LATE_CBMEM_INIT

In preparation to remove the static CBMEM allocator, tag the chipsets
that still do not implement get_top_of_ram() for romstage.

LATE_CBMEM_INIT also implies BROKEN_CAR_MIGRATE.

Change-Id: Iad359db2e65ac15c54ff6e9635429628e4db6fde
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/7850
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Aaron Durbin <adurbin@google.com>
Tested-by: build bot (Jenkins)

src/arch/x86/boot/cbmem.c

@@ -56,7 +56,7 @@ void set_top_of_ram(uint64_t ramtop)
 }
 #endif /* !__PRE_RAM__ */
 
-#if CONFIG_BROKEN_CAR_MIGRATE || !defined(__PRE_RAM__)
+#if IS_ENABLED(CONFIG_LATE_CBMEM_INIT)
 unsigned long __attribute__((weak)) get_top_of_ram(void)
 {
 	printk(BIOS_WARNING, "WARNING: you need to define get_top_of_ram() for your chipset\n");