Bluetooth: Optimize connection parameter lookup for LE connections

When we get an LE connection complete event there's really no reason to
look through the entire connection parameter list as the entry should be
present in the hdev->pend_le_conns list too. This patch changes the
lookup code to do a more restricted lookup only in the pend_le_conns
list.

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