of1.0: fix import error

Fix the  533fd972519871afe441d365f911a2970fe0875f commit.

This patch fixes the following issue.

Traceback (most recent call last):
  File "/opt/stack/ryu/bin/ryu-manager", line 42, in <module>
    from ryu.base.app_manager import AppManager
  File "/opt/stack/ryu/ryu/base/app_manager.py", line 25, in <module>
    from ryu.controller.handler import register_instance
  File "/opt/stack/ryu/ryu/controller/handler.py", line 20, in <module>
    from ryu.controller import ofp_event
  File "/opt/stack/ryu/ryu/controller/ofp_event.py", line 75, in <module>
    _create_ofp_msg_ev_from_module(m)
  File "/opt/stack/ryu/ryu/controller/ofp_event.py", line 60, in _create_ofp_msg_ev_from_module
    mod = utils.import_module(modname)
  File "/opt/stack/ryu/ryu/utils.py", line 35, in import_module
    __import__(name)
  File "/opt/stack/ryu/ryu/ofproto/ofproto_v1_0_parser.py", line 26, in <module>
    import utils.round_up
ImportError: No module named utils.round_up

Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>