openvswitch: flow_netlink: Use pr_fmt to OVS_NLERR output

Add "openvswitch: " prefix to OVS_NLERR output
to match the other OVS_NLERR output of datapath.c

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>

net/openvswitch/flow_netlink.c

@@ -16,6 +16,8 @@
  * 02110-1301, USA
  */
 
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
 #include "flow.h"
 #include "datapath.h"
 #include <linux/uaccess.h>