src/security: Remove unused <stdlib.h>

Change-Id: I0b5c375baf7911ebced2f8c43a88aae014c877ad
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33694
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/security/vboot/secdata_tpm.c

@@ -34,7 +34,6 @@
 
 #include <security/vboot/antirollback.h>
 #include <security/vboot/tpm_common.h>
-#include <stdlib.h>
 #include <string.h>
 #include <security/tpm/tspi.h>
 #include <vb2_api.h>