openvswitch: remove duplicated include from vport-vxlan.c

Remove duplicated include.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Jesse Gross <jesse@nicira.com>

net/openvswitch/vport-vxlan.c

@@ -29,7 +29,6 @@
 #include <net/ip.h>
 #include <net/udp.h>
 #include <net/ip_tunnels.h>
-#include <net/udp.h>
 #include <net/rtnetlink.h>
 #include <net/route.h>
 #include <net/dsfield.h>