Bluetooth: Fix setting local name to the existing value

If user space attempts to set the local name to the same value that's
already set we should simply return a direct command complete for this
mgmt command.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>