leds: trigger: netdev: Fix kernel panic on interface rename trig notify

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

leds: trigger: netdev: Fix kernel panic on interface rename trig notify

Commit d5e01266e7f5 ("leds: trigger: netdev: add additional specific link

speed mode") in the various changes, reworked the way to set the LINKUP

mode in commit cee4bd16c319 ("leds: trigger: netdev: Recheck

NETDEV_LED_MODE_LINKUP on dev rename") and moved it to a generic function.

This changed the logic where, in the previous implementation the dev

from the trigger event was used to check if the carrier was ok, but in

the new implementation with the generic function, the dev in

trigger_data is used instead.

This is problematic and cause a possible kernel panic due to the fact

that the dev in the trigger_data still reference the old one as the

new one (passed from the trigger event) still has to be hold and saved

in the trigger_data struct (done in the NETDEV_REGISTER case).

On calling of get_device_state(), an invalid net_dev is used and this

cause a kernel panic.

To handle this correctly, move the call to get_device_state() after the

new net_dev is correctly set in trigger_data (in the NETDEV_REGISTER

case) and correctly parse the new dev.