x86: Change condition for using CAR

At present we assume that CAR (Cache-as-RAM) is used if HOBs (Hand-off
blocks) are not, since HOBs typically indicate that an FSP is in use, and
FSPs handle the CAR init.

However this is a bit indirect, and for FSP2 machines which use their own
CAR implementation (such as apollolake) but use the FSP for other
functions, the logic is wrong.

To fix this, add a dedicated Kconfig option to indicate when CAR is used.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: fix a typo in the commit message]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 314f8de..47bf28c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -364,6 +364,14 @@
 	  Note: Without this binary U-Boot will not be able to set up its
 	  SDRAM so will not boot.
 
+config USE_CAR
+	bool "Use Cache-As-RAM (CAR) to get temporary RAM at start-up"
+	default y if !HAVE_FSP
+	help
+	  Select this option if your board uses CAR init code, typically in a
+	  car.S file, to get some initial memory for code execution. This is
+	  common with Intel CPUs which don't use FSP.
+
 choice
 	prompt "FSP version"
 	depends on HAVE_FSP