nl80211: Remove a misleading label in 'nl80211_trigger_scan()'

nl80211: Remove a misleading label in 'nl80211_trigger_scan()'

Since commit 5fe231e87372 ("cfg80211: vastly simplify locking"), the
'unlock' label at the end of 'nl80211_trigger_scan()' is useless and
misleading, because nothing is unlocked there.

Direct return can be used instead of 'err = -<error code>; goto unlock;'
construction.

Remove this label and simplify code accordingly.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/20200712173539.274395-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Johannes Berg <johannes.berg@intel.com>