Bluetooth: Do not allow LE connection if LE is not enabled

Kernel gives possibility to enable/disable LE host support.
There is flag HCI_LE_ENABLED which is set when this support is enabled
and some parts of the code checks this flag e.g. SMP
However it is still possible to make LE connection if LE Host support is
disabled, what might be confused for remote device.
This patch makes sure that kernel will not send HCI LE Create Connection
if LE HOST support is not enabled.

Signed-off-by: Lukasz Rymanowski <lukasz.rymanowski@tieto.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>