Bluetooth: Check for flag instead of features in update_adv_data()

It's better to check for the device flag instead of device features so
that we avoid unnecessary HCI commands when the feature is supported but
disabled (i.e. the flag is unset).

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>