feat: cleanup init code, small other refactors

kernel/mem/malloc.c

@@ -725,7 +725,7 @@ void free(void *ptr) {
 
 
 void *calloc(size_t nobj, size_t size) {
-    int real_size;
+    size_t real_size;
     void *p;
 
     real_size = nobj * size;