Bluetooth: Fix iterating wrong list in hci_remove_irk()

We should be iterating hdev->identity_resolving_keys in the
hci_remove_irk() function instead of hdev->long_term_keys. This patch
fixes the issue.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>