This replaces occurences of

    foo_t *foo = m_new_obj(foo_t);
    foo->base.type = &foo_type;

with

    foo_t *foo = mp_obj_malloc(foo_t, &foo_type);

Excludes any places where base is a sub-field or when new0/memset is used.
Signed-off-by: NJim Mussared <jim.mussared@gmail.com>