soc/intel/baytrail/northcluster.c: Add missing include

Replace unused <stddef.h> with missing <stdint.h>.

Change-Id: I85745c331c81a419cef4547fc1c67bde1e202e8f
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43346
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/baytrail/northcluster.c

@@ -5,7 +5,7 @@
 #include <device/pci_ids.h>
 #include <vendorcode/google/chromeos/chromeos.h>
 #include <acpi/acpi.h>
-#include <stddef.h>
+#include <stdint.h>
 #include <soc/iomap.h>
 #include <soc/iosf.h>
 #include <soc/pci_devs.h>