nfp: flower: avoid newline at the end of message in NL_SET_ERR_MSG_MOD

Fix the following coccicheck warning:

    drivers/net/ethernet/netronome/nfp/flower/action.c:959:7-69: WARNING avoid newline at end of message in NL_SET_ERR_MSG_MOD
Signed-off-by: NNiklas Söderlund <niklas.soderlund@corigine.com>
Signed-off-by: NSimon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20220312095823.2425775-1-niklas.soderlund@corigine.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/netronome/nfp/flower/action.c

@@ -956,7 +956,7 @@ nfp_flower_meter_action(struct nfp_app *app,
 	meter_id = action->hw_index;
 	if (!nfp_flower_search_meter_entry(app, meter_id)) {
 		NL_SET_ERR_MSG_MOD(extack,
-				   "can not offload flow table with unsupported police action.\n");
+				   "can not offload flow table with unsupported police action.");
 		return -EOPNOTSUPP;
 	}