spl: Allow PCH drivers to be used in SPL

Add an option for building Platorm Controller Hub drivers in SPL.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/Makefile b/drivers/Makefile
index 00dc041..34c55bf 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -34,6 +34,7 @@
 obj-$(CONFIG_SPL_ETH_SUPPORT) += net/phy/
 obj-$(CONFIG_SPL_USBETH_SUPPORT) += net/phy/
 obj-$(CONFIG_SPL_PCI_SUPPORT) += pci/
+obj-$(CONFIG_SPL_PCH_SUPPORT) += pch/
 obj-$(CONFIG_SPL_RTC_SUPPORT) += rtc/
 obj-$(CONFIG_SPL_TIMER_SUPPORT) += timer/
 obj-$(CONFIG_SPL_MUSB_NEW_SUPPORT) += usb/musb-new/