memblock region iteration can now be bounded to a certain memory range

sandbox/memblock/main.c

@@ -48,7 +48,7 @@ int main(int argc, const char **argv)
 	}
 
 	printf("free regions:\n");
-	for_each_free_mem_range(&it, 0, 0x100000) {
+	for_each_free_mem_range(&it, 0, ULLONG_MAX) {
 		printf("\t%08" PRIxPTR "-%08" PRIxPTR "\n",
 				it.base,
 				it.limit);