dm: x86: Add a driver for Intel PCH7

At some point we may need to distinguish between different types of PCHs,
but for existing supported platforms we only need to worry about version 7
and version 9 bridges. Add a driver for the PCH7.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/pch/Makefile b/drivers/pch/Makefile
index d69a99c..33aa727 100644
--- a/drivers/pch/Makefile
+++ b/drivers/pch/Makefile
@@ -3,3 +3,4 @@
 #
 
 obj-y += pch-uclass.o
+obj-y += pch7.o