staging: rtl8192e: Unlock wx_mutex not in rtllib_wx_set_scan

staging: rtl8192e: Unlock wx_mutex not in rtllib_wx_set_scan

On start of rtllib_wx_set_scan lock was taken with
mutex_lock(&ieee->wx_mutex). Unlocking was done at the end of
schedule_work(&ieee->wx_sync_scan_wq) which lead to the error "lock held
when returning to user space!". Pushing lock to beginning of
ieee->wx_sync_scan_wq to improve overview. Removed lock from
rtllib_wx_set_scan as ieee->state, ieee->iw_mode and ieee->proto_started
are not protected in many other places.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/20230516192206.GA7710@matrix-ESPRIMO-P710
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>