tree: Drop unused <stdlib.h>

Change-Id: Ie7e36cfa5a09d94bb58f12f9bd262255a630424c
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81819
Reviewed-by: Yidi Lin <yidilin@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/soc/mediatek/common/early_init.c

@@ -2,7 +2,6 @@
 
 #include <assert.h>
 #include <soc/early_init.h>
-#include <stdlib.h>
 #include <string.h>
 
 static struct early_init_data *find_early_init(void)