net: stmmac: Disable Tx queues when reconfiguring the interface

In the Linux kernel, the following vulnerability has been resolved:

net: stmmac: Disable Tx queues when reconfiguring the interface

The Tx queues were not disabled in situations where the driver needed to

stop the interface to apply a new configuration. This could result in a

kernel panic when doing any of the 3 following actions:

* reconfiguring the number of queues (ethtool -L)

* reconfiguring the size of the ring buffers (ethtool -G)

* installing/removing an XDP program (ip l set dev ethX xdp)

Prevent the panic by making sure netif_tx_disable is called when stopping

an interface.

Without this patch, the following kernel panic can be observed when doing

any of the actions above:

Unable to handle kernel paging request at virtual address ffff80001238d040

[....]

Call trace:

dwmac4_set_addr+0x8/0x10

dev_hard_start_xmit+0xe4/0x1ac

sch_direct_xmit+0xe8/0x39c

__dev_queue_xmit+0x3ec/0xaf0

dev_queue_xmit+0x14/0x20

[...]

[ end trace 0000000000000002 ]---