nimble/gap: Fix for resolving list peer removal

This commmit aims to fix an issue where deleting
peer from resolving list would fail due to
lack of IRK on the list.

nimble/host/src/ble_gap.c

@@ -6202,7 +6202,12 @@ ble_gap_unpair(const ble_addr_t *peer_addr)
 
     rc = ble_hs_pvcy_remove_entry(peer_addr->type,
                              peer_addr->val);
-    if (rc != 0) {
+
+    /* We allow BLE_ERR_UNK_CONN_ID as the IRK of the peer might not be
+     * present on the resolving list, but we still should be able to
+     * remove that entry.
+     */
+    if (rc != 0 && rc != (BLE_HS_ERR_HCI_BASE + BLE_ERR_UNK_CONN_ID)) {
         return rc;
     }