dm: x86: Add a uclass for a Platform Controller Hub

Add a simple uclass for this chip which is often found in x86 systems
where the CPU is a separate device.

The device can have children, so make it scan the device tree for these.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 67a34d8..fe022f6 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -20,6 +20,7 @@
 ifndef CONFIG_DM_PCI
 obj-$(CONFIG_PCI) += pci_type1.o
 endif
+obj-y	+= pch-uclass.o
 obj-y	+= relocate.o
 obj-y += physmem.o
 obj-$(CONFIG_X86_RAMTEST) += ramtest.o