wifi-scripts: fix MLO AP setup with disabled radios

wifi-scripts: fix MLO AP setup with disabled radios

When an MLO interface specifies multiple radios and the first radio
is disabled, the MLO configuration was never created because the code
only attempted to create it when processing the first device in the
list (which gets skipped if disabled).

Fix by creating the MLO config for the first enabled device instead
of only when processing dev_names[0].

Reported-by: Michael-cy Lee (李峻宇) <[email protected]>
Signed-off-by: Felix Fietkau <[email protected]>