Bluetooth: Write LE Host Supported command

This patch adds a handler to Write LE Host Supported command complete
events. Once this commands has completed successfully, we should
read the extended LMP features and update the extfeatures field in
hci_dev.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>