soc/intel/alderlake: Fix non-local header treated as local

Change-Id: I93e6989633b9ac1b2738b812e3f8b442ecfdcbf0
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81813
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Varshit Pandya <pandyavarshit@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/alderlake/systemagent.c

@@ -19,7 +19,7 @@
 #include <soc/soc_chip.h>
 #include <soc/systemagent.h>
 #include <spi_flash.h>
-#include "stddef.h"
+#include <stddef.h>
 
 /*
  * SoC implementation