Revert "net: ipv4: handle DSA enabled master network devices"

This reverts commit 728c0208.

Since 2015 DSA has gained more integration with the network stack, we
can now have the same functionality without explicitly open-coding for
it:
- It now opens the DSA master netdevice automatically whenever a user
  netdevice is opened.
- The master and switch interfaces are coupled in an upper/lower
  hierarchy using the netdev adjacency lists.

In the nfsroot example below, the interface chosen by autoconfig was
swp3, and every interface except that and the DSA master, eth1, was
brought down afterwards:

[    8.714215] mscc_felix 0000:00:00.5 swp0 (uninitialized): PHY [0000:00:00.3:10] driver [Microsemi GE VSC8514 SyncE] (irq=POLL)
[    8.978041] mscc_felix 0000:00:00.5 swp1 (uninitialized): PHY [0000:00:00.3:11] driver [Microsemi GE VSC8514 SyncE] (irq=POLL)
[    9.246134] mscc_felix 0000:00:00.5 swp2 (uninitialized): PHY [0000:00:00.3:12] driver [Microsemi GE VSC8514 SyncE] (irq=POLL)
[    9.486203] mscc_felix 0000:00:00.5 swp3 (uninitialized): PHY [0000:00:00.3:13] driver [Microsemi GE VSC8514 SyncE] (irq=POLL)
[    9.512827] mscc_felix 0000:00:00.5: configuring for fixed/internal link mode
[    9.521047] mscc_felix 0000:00:00.5: Link is Up - 2.5Gbps/Full - flow control off
[    9.530382] device eth1 entered promiscuous mode
[    9.535452] DSA: tree 0 setup
[    9.539777] printk: console [netcon0] enabled
[    9.544504] netconsole: network logging started
[    9.555047] fsl_enetc 0000:00:00.2 eth1: configuring for fixed/internal link mode
[    9.562790] fsl_enetc 0000:00:00.2 eth1: Link is Up - 1Gbps/Full - flow control off
[    9.564661] 8021q: adding VLAN 0 to HW filter on device bond0
[    9.637681] fsl_enetc 0000:00:00.0 eth0: PHY [0000:00:00.0:02] driver [Qualcomm Atheros AR8031/AR8033] (irq=POLL)
[    9.655679] fsl_enetc 0000:00:00.0 eth0: configuring for inband/sgmii link mode
[    9.666611] mscc_felix 0000:00:00.5 swp0: configuring for inband/qsgmii link mode
[    9.676216] 8021q: adding VLAN 0 to HW filter on device swp0
[    9.682086] mscc_felix 0000:00:00.5 swp1: configuring for inband/qsgmii link mode
[    9.690700] 8021q: adding VLAN 0 to HW filter on device swp1
[    9.696538] mscc_felix 0000:00:00.5 swp2: configuring for inband/qsgmii link mode
[    9.705131] 8021q: adding VLAN 0 to HW filter on device swp2
[    9.710964] mscc_felix 0000:00:00.5 swp3: configuring for inband/qsgmii link mode
[    9.719548] 8021q: adding VLAN 0 to HW filter on device swp3
[    9.747811] Sending DHCP requests ..
[   12.742899] mscc_felix 0000:00:00.5 swp1: Link is Up - 1Gbps/Full - flow control rx/tx
[   12.743828] mscc_felix 0000:00:00.5 swp0: Link is Up - 1Gbps/Full - flow control off
[   12.747062] IPv6: ADDRCONF(NETDEV_CHANGE): swp1: link becomes ready
[   12.755216] fsl_enetc 0000:00:00.0 eth0: Link is Up - 1Gbps/Full - flow control rx/tx
[   12.766603] IPv6: ADDRCONF(NETDEV_CHANGE): swp0: link becomes ready
[   12.783188] mscc_felix 0000:00:00.5 swp2: Link is Up - 1Gbps/Full - flow control rx/tx
[   12.785354] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[   12.799535] IPv6: ADDRCONF(NETDEV_CHANGE): swp2: link becomes ready
[   13.803141] mscc_felix 0000:00:00.5 swp3: Link is Up - 1Gbps/Full - flow control rx/tx
[   13.811646] IPv6: ADDRCONF(NETDEV_CHANGE): swp3: link becomes ready
[   15.452018] ., OK
[   15.470336] IP-Config: Got DHCP answer from 10.0.0.1, my address is 10.0.0.39
[   15.477887] IP-Config: Complete:
[   15.481330]      device=swp3, hwaddr=00:04:9f:05:de:0a, ipaddr=10.0.0.39, mask=255.255.255.0, gw=10.0.0.1
[   15.491846]      host=10.0.0.39, domain=(none), nis-domain=(none)
[   15.498429]      bootserver=10.0.0.1, rootserver=10.0.0.1, rootpath=
[   15.498481]      nameserver0=8.8.8.8
[   15.627542] fsl_enetc 0000:00:00.0 eth0: Link is Down
[   15.690903] mscc_felix 0000:00:00.5 swp0: Link is Down
[   15.745216] mscc_felix 0000:00:00.5 swp1: Link is Down
[   15.800498] mscc_felix 0000:00:00.5 swp2: Link is Down

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>