sfc: fix a double-free bug in efx_probe_filters

In efx_probe_filters, the channel->rps_flow_id is freed in a
efx_for_each_channel marco  when success equals to 0.
However, after the following call chain:

ef100_net_open
  |-> efx_probe_filters
  |-> ef100_net_stop
        |-> efx_remove_filters

The channel->rps_flow_id is freed again in the efx_for_each_channel of
efx_remove_filters, triggering a double-free bug.

Fixes: a9dc3d5 ("sfc_ef100: RX filter table management and related gubbins")
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
Link: https://lore.kernel.org/r/20231225112915.3544581-1-alexious@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: AlexiousLu

drivers/net/ethernet/sfc/rx_common.c

@@ -823,8 +823,10 @@ int efx_probe_filters(struct efx_nic *efx)
 		}
 
 		if (!success) {
-			efx_for_each_channel(channel, efx)
+			efx_for_each_channel(channel, efx) {
 				kfree(channel->rps_flow_id);
+				channel->rps_flow_id = NULL;
+			}
 			efx->type->filter_table_remove(efx);
 			rc = -ENOMEM;
 			goto out_unlock;