x86: kconfig: Imply ENABLE_MRC_CACHE in the platform Kconfig

Platform knows whether MRC cache is implemented, but using it can
be a choice of a specific board.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/broadwell/Kconfig b/arch/x86/cpu/broadwell/Kconfig
index f3006c3..a9a461d 100644
--- a/arch/x86/cpu/broadwell/Kconfig
+++ b/arch/x86/cpu/broadwell/Kconfig
@@ -8,6 +8,7 @@
 	select CACHE_MRC_BIN
 	select ARCH_EARLY_INIT_R
 	imply HAVE_INTEL_ME
+	imply ENABLE_MRC_CACHE
 
 if INTEL_BROADWELL