x86: fsp: Save stack address to CMOS for next S3 boot

At the end of pre-relocation phase, save the new stack address
to CMOS and use it as the stack on next S3 boot for fsp_init()
continuation function.

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/cpu/cpu.c b/arch/x86/cpu/cpu.c
index f686ad4..f86eaa9 100644
--- a/arch/x86/cpu/cpu.c
+++ b/arch/x86/cpu/cpu.c
@@ -278,6 +278,14 @@
 	high_table_reserve();
 #endif
 
+#if defined(CONFIG_HAVE_ACPI_RESUME) && defined(CONFIG_HAVE_FSP)
+	/*
+	 * Save stack address to CMOS so that at next S3 boot,
+	 * we can use it as the stack address for fsp_contiue()
+	 */
+	fsp_save_s3_stack();
+#endif
+
 	return 0;
 }
 #endif