src/device: Clean up includes

Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Change-Id: Idd78271f2158bdc29ce9ac8d81f46ad8cbe84c5e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68205
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
diff --git a/src/device/dram/spd.c b/src/device/dram/spd.c
index b6246ae..deff674 100644
--- a/src/device/dram/spd.c
+++ b/src/device/dram/spd.c
@@ -2,6 +2,7 @@
 
 #include <device/dram/spd.h>
 #include <spd.h>
+#include <stddef.h>
 
 const char *spd_manufacturer_name(const uint16_t mod_id)
 {