Bluetooth: Refactor hci_connect_le

This patch does some code refactoring in hci_connect_le() by moving
the exception code into if statements and letting the main flow in
first level of function scope. It also adds extra comments to improve
the code readability.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>