lib: Remove unused <stdlib.h> and use <types.h> when appropriate

Unused <stdlib.h> found using:
diff <(git grep -l '#include <stdlib.h>' -- src/) <(git grep -l 'memalign(\|malloc(\|calloc(\|free(' -- src/)

Change-Id: I5ad171679cbfa67d522bd1105fb58e0f84b9cb89
Signed-off-by: Elyes Haouas <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60621
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <martinroth@google.com>

src/lib/hardwaremain.c

@@ -19,7 +19,6 @@
 #include <device/device.h>
 #include <device/pci.h>
 #include <program_loading.h>
-#include <stdlib.h>
 #include <thread.h>
 #include <timer.h>
 #include <timestamp.h>