openvswitch: Drop user features if old user space attempted to create datapath

Drop user features if an outdated user space instance that does not
understand the concept of user_features attempted to create a new
datapath.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Jesse Gross <jesse@nicira.com>

diff --cc include/uapi/linux/openvswitch.h
Simple merge

diff --cc net/openvswitch/datapath.c
Simple merge