connmgr: Do not use OFPRR_METER_DELETE before OF1.4

OFPRR_METER_DELETE was introduced in OF1.4 however meters were introduced
in OF1.3.

Regardless of the OF version when flows are deleted cause flows to be
deleted handle_delete_meter() calls delete_flows__() with
OFPRR_METER_DELETE as the reason.

In order to avoid sending OFPRR_METER_DELETE to controllers connected
using OF1.3 map OFPRR_METER_DELETE to OFPRR_DELETE which exists in that
version.

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Ben Pfaff <blp@nicira.com>