Bluetooth: Add LE Local Features reading support

To be able to make the appropriate decisions for some LE procedures we
need to know the LE features that the local controller supports.
Therefore, it's important to have the LE Read Local Supported Features
HCI comand as part of the HCI init sequence.

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>