net/mlx5: Fix steering rules cleanup

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Fix steering rules cleanup vport's mc, uc and multicast rules are not deleted in teardown path when EEH happens. Since the vport's promisc settings(uc, mc and all) in firmware are reset after EEH, mlx5 driver will try to delete the above rules in the initialization path. This cause kernel crash because these software rules are no longer valid. Fix by nullifying these rules right after delete to avoid accessing any dangling pointers. Call Trace: __list_del_entry_valid+0xcc/0x100 (unreliable) tree_put_node+0xf4/0x1b0 [mlx5_core] tree_remove_node+0x30/0x70 [mlx5_core] mlx5_del_flow_rules+0x14c/0x1f0 [mlx5_core] esw_apply_vport_rx_mode+0x10c/0x200 [mlx5_core] esw_update_vport_rx_mode+0xb4/0x180 [mlx5_core] esw_vport_change_handle_locked+0x1ec/0x230 [mlx5_core] esw_enable_vport+0x130/0x260 [mlx5_core] mlx5_eswitch_enable_sriov+0x2a0/0x2f0 [mlx5_core] mlx5_device_enable_sriov+0x74/0x440 [mlx5_core] mlx5_load_one+0x114c/0x1550 [mlx5_core] mlx5_pci_resume+0x68/0xf0 [mlx5_core] eeh_report_resume+0x1a4/0x230 eeh_pe_dev_traverse+0x98/0x170 eeh_handle_normal_event+0x3e4/0x640 eeh_handle_event+0x4c/0x370 eeh_event_handler+0x14c/0x210 kthread+0x168/0x1b0 ret_from_kernel_thread+0x5c/0x84