Bluetooth: Use hci_pend_le_action_lookup to look up report entries

Instead of looking through the entire list of entries we can more
efficiently use the new hci_pend_le_action_lookup() function to look up
entries specifically in the pend_le_reports list. Since the search is
now limited to the right list we can also remove an unnecessary check
for list_empty() before the lookup.

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