dpif-netlink: Suppress DPIF_FP_PROBE here instead of in ofproto-dpif.

dpif-netlink: Suppress DPIF_FP_PROBE here instead of in ofproto-dpif.

Commit 22b4ccf4f (ofproto-dpif: Don't try to use dpif_probe_feature() with
Windows datapath.) stopped ofproto-dpif from trying to use the DPIF_FP_PROBE
feature of the datapath interface, because it doesn't work with Windows
yet.  However, it was *too* broad--it also stopped ofproto-dpif from
using DPIF_FP_PROBE with the netdev datapath, which still does support
DPIF_FP_PROBE on Windows.  This commit moves disabling DPIF_FP_PROBE a
couple of layers down, to a place where the two datapaths can be easily
distinguished.

Reported-by: Gurucharan Shetty <shettyg@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>