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/imd_cbmem.c

@@ -7,7 +7,7 @@
 #include <cbmem.h>
 #include <imd.h>
 #include <lib.h>
-#include <stdlib.h>
+#include <types.h>
 
 /* The program loader passes on cbmem_top and the program entry point
    has to fill in the _cbmem_top_ptr symbol based on the calling arguments. */