x86: fsp: Mark memory used by U-Boot as reserved in the E820 table for S3

U-Boot itself as well as everything that is consumed by U-Boot (like
heap, stack, dtb, etc) needs to be reserved and reported in the E820
table when S3 resume is on.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stefan Roese <sr@denx.de>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b568852..5322eff 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -601,6 +601,14 @@
 	  is done, U-Boot needs to find out the wakeup vector provided by OSes
 	  and jump there.
 
+config STACK_SIZE
+	hex
+	depends on HAVE_ACPI_RESUME
+	default 0x1000
+	help
+	  Estimated U-Boot's runtime stack size that needs to be reserved
+	  during an ACPI S3 resume.
+
 config MAX_PIRQ_LINKS
 	int
 	default 8