wifi-scripts: fix spurious teardown on config_change during setup

wifi-scripts: fix spurious teardown on config_change during setup

When config_change is set during an active setup (e.g. by a concurrent
reconf call), wdev_mark_up() attempted to call setup() while still in
"setup" state. Since setup() requires state "up" or "down", it silently
returned, leaving the state as "setup". The subsequent wdev_setup_cb()
then treated this as a setup failure, triggering an unnecessary
teardown+restart cycle.

Fix this by removing the config_change handling from wdev_mark_up() and
moving it to wdev_setup_cb() instead. wdev_mark_up() now always
transitions to "up" state. When wdev_setup_cb() runs afterwards and
finds the device already "up" with config_change set, it initiates a
clean re-setup from the "up" state where setup() can run.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
(cherry picked from commit 3553eda28379f1074b8c2cc4d3ab9930552f0cad)