x86: Convert INTEL_ICH6_GPIO to Kconfig

This converts Intel ICH6 GPIO driver to Kconfig, and add it to the
imply list of platform drivers.

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 ce0c454..7ec46e9 100644
--- a/arch/x86/cpu/quark/Kconfig
+++ b/arch/x86/cpu/quark/Kconfig
@@ -13,6 +13,7 @@
 	imply ENV_IS_IN_SPI_FLASH
 	imply ETH_DESIGNWARE
 	imply ICH_SPI
+	imply INTEL_ICH6_GPIO
 	imply MMC
 	imply MMC_PCI
 	imply MMC_SDHCI