Bluetooth: trivial: Shorten variable scope

Make code more clear by moving sk and bt vars to the place where
they are actually used.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>