arch/x86: Drop leftover ROMCC support

Remove the last bits of building romstage with romcc.

Change-Id: I70bb1ed23a5aeb87bf7641e0b0bd604a4e622e61
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/26807
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

src/cpu/Kconfig

@@ -8,7 +8,7 @@ if ARCH_X86
 
 config CACHE_AS_RAM
 	bool
-	default !ROMCC
+	default y
 
 config NO_CAR_GLOBAL_MIGRATION
 	bool