cgcreate: add err check

cgcreate: add err check

cgroup still can be created even if giving invalid -d,-f,-s parameter
e.g.
        cgcreate -g cpu:/test -d 888
        "888" is invalid, but test will be cgreated.

        So we should exit if -d,-f or -s is invalid

v2:
 - add nonzero return value

Signed-off-by: Libo Chen <clbchenlibo.chen@huawei.com>
Acked-by: Ivana Hutarova Varekova <varekova@redhat.com>