sb/intel/lynxpoint: Add native PCH init

Implement native PCH initialisation for Lynx Point. This is only needed
when MRC.bin is not used.

Change-Id: I36867bdc8b20000e44ff9d0d7b2c0d63952bd561
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64181
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/southbridge/intel/lynxpoint/Makefile.inc b/src/southbridge/intel/lynxpoint/Makefile.inc
index 5874c4f..bba89f4 100644
--- a/src/southbridge/intel/lynxpoint/Makefile.inc
+++ b/src/southbridge/intel/lynxpoint/Makefile.inc
@@ -36,6 +36,7 @@
 romstage-y += pmutil.c
 
 romstage-$(CONFIG_USE_NATIVE_RAMINIT) += early_pch_native.c early_usb_native.c iobp.c thermal.c
+subdirs-$(CONFIG_USE_NATIVE_RAMINIT) += hsio
 
 ifeq ($(CONFIG_INTEL_LYNXPOINT_LP),y)
 romstage-y += lp_gpio.c