src/soc/intel/skylake/chip.h: Add smbios.h for Type9 Entries

In order to add the smbios_slot_desc for the SMBIOS Type9 entries into
the devicetree, and not use numbers but strings like
"SlotTypePciExpressGen3X4", smbios.h needs to be included in the
static.c.

Change-Id: Iace547868b4ce8eb7d3624baf1abd1187c1e5f51
Signed-off-by: Christian Walter <christian.walter@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32965
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/skylake/chip.h

@@ -34,6 +34,7 @@
 #include <soc/serialio.h>
 #include <soc/usb.h>
 #include <soc/vr_config.h>
+#include <smbios.h>
 
 #define MAX_PEG_PORTS	3