Bluetooth: Fix specifying role for LE connections

The hci_connect_le_scan() is (as the name implies) a master/central
role API, so it makes no sense in passing a role parameter to it. At
the same time this patch also fixes the direct advertising support for
LE L2CAP sockets where we now call the more appropriate hci_le_connect()
API if slave/peripheral role is desired.

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