x86: quark: Specify X86_TSC_TIMER_EARLY_FREQ

Specify X86_TSC_TIMER_EARLY_FREQ for Quark SoC so that TSC as
the early timer can be supported.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/quark/Kconfig b/arch/x86/cpu/quark/Kconfig
index 76f1592..3a18cb0 100644
--- a/arch/x86/cpu/quark/Kconfig
+++ b/arch/x86/cpu/quark/Kconfig
@@ -130,4 +130,8 @@
 	  Space in bytes in eSRAM used as Cache-As-ARM (CAR).
 	  Note this size must not exceed eSRAM's total size.
 
+config X86_TSC_TIMER_EARLY_FREQ
+	int
+	default 400
+
 endif