idpf: detach and close netdevs while handling a reset

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

idpf: detach and close netdevs while handling a reset

Protect the reset path from callbacks by setting the netdevs to detached
state and close any netdevs in UP state until the reset handling has
completed. During a reset, the driver will de-allocate resources for the
vport, and there is no guarantee that those will recover, which is why the
existing vport_ctrl_lock does not provide sufficient protection.

idpf_detach_and_close() is called right before reset handling. If the
reset handling succeeds, the netdevs state is recovered via call to
idpf_attach_and_open(). If the reset handling fails the netdevs remain
down. The detach/down calls are protected with RTNL lock to avoid racing
with callbacks. On the recovery side the attach can be done without
holding the RTNL lock as there are no callbacks expected at that point,
due to detach/close always being done first in that flow.

The previous logic restoring the netdevs state based on the
IDPF_VPORT_UP_REQUESTED flag in the init task is not needed anymore, hence
the removal of idpf_set_vport_state(). The IDPF_VPORT_UP_REQUESTED is
still being used to restore the state of the netdevs following the reset,
but has no use outside of the reset handling flow.

idpf_init_hard_reset() is converted to void, since it was used as such and
there is no error handling being done based on its return value.

Before this change, invoking hard and soft resets simultaneously will
cause the driver to lose the vport state:
ip -br a
<inf> UP
echo 1 > /sys/class/net/ens801f0/device/reset& \
ethtool -L ens801f0 combined 8
ip -br a
<inf> DOWN
ip link set <inf> up
ip -br a
<inf> DOWN

Also in case of a failure in the reset path, the netdev is left
exposed to external callbacks, while vport resources are not
initialized, leading to a crash on subsequent ifup/down:
[408471.398966] idpf 0000:83:00.0: HW reset detected
[408471.411744] idpf 0000:83:00.0: Device HW Reset initiated
[408472.277901] idpf 0000:83:00.0: The driver was unable to contact the device's firmware. Check that the FW is running. Driver state= 0x2
[408508.125551] BUG: kernel NULL pointer dereference, address: 0000000000000078
[408508.126112] #PF: supervisor read access in kernel mode
[408508.126687] #PF: error_code(0x0000) - not-present page
[408508.127256] PGD 2aae2f067 P4D 0
[408508.127824] Oops: Oops: 0000 [#1] SMP NOPTI
...
[408508.130871] RIP: 0010:idpf_stop+0x39/0x70 [idpf]
...
[408508.139193] Call Trace:
[408508.139637] <TASK>
[408508.140077] __dev_close_many+0xbb/0x260
[408508.140533] __dev_change_flags+0x1cf/0x280
[408508.140987] netif_change_flags+0x26/0x70
[408508.141434] dev_change_flags+0x3d/0xb0
[408508.141878] devinet_ioctl+0x460/0x890
[408508.142321] inet_ioctl+0x18e/0x1d0
[408508.142762] ? _copy_to_user+0x22/0x70
[408508.143207] sock_do_ioctl+0x3d/0xe0
[408508.143652] sock_ioctl+0x10e/0x330
[408508.144091] ? find_held_lock+0x2b/0x80
[408508.144537] __x64_sys_ioctl+0x96/0xe0
[408508.144979] do_syscall_64+0x79/0x3d0
[408508.145415] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[408508.145860] RIP: 0033:0x7f3e0bb4caff