openvswitch: Simplify genetlink code.

Following patch get rid of struct genl_family_and_ops which is
redundant due to changes to struct genl_family.

Signed-off-by: Kyle Mestery <mestery@noironetworks.com>
Acked-by: Kyle Mestery <mestery@noironetworks.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>