Bluetooth: Fix LE reconnection logic

We can't use hci_explicit_connect_lookup() since that would only cover
explicit connections, leaving normal reconnections completely
untouched. Not using it in turn means leaving out entries in
pend_le_reports.

To fix this and simplify the logic move conn params from the reports
list to the pend_le_conns list for the duration of an explicit
connect. Once the connect is complete move the params back to the
pend_le_reports list. This also means that the explicit connect lookup
function only needs to look into the pend_le_conns list.

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