x86: Add ENABLE_MRC_CACHE Kconfig option

Create a Kconfig option for enabling MRC cache.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index bf09b21..f92082d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -239,6 +239,14 @@
 	help
 	  Additional size of malloc() pool before relocation.
 
+config ENABLE_MRC_CACHE
+	bool "Enable MRC cache"
+	depends on !EFI && !SYS_COREBOOT
+	help
+	  Enable this feature to cause MRC data to be cached in NV storage
+	  to be used for speeding up boot time on future reboots and/or
+	  power cycles.
+
 config SMP
 	bool "Enable Symmetric Multiprocessing"
 	default n