host: sm: callback is not triggered in case of invalid key size

pairing callback was not triggered in case of encryption key size checks failed. Fix it by setting the res->enc_cb value to 1 for check failure.

nimble/host/src/ble_sm.c

@@ -1921,18 +1921,22 @@ ble_sm_pair_rsp_rx(uint16_t conn_handle, struct os_mbuf **om,
         if (rsp->max_enc_key_size < BLE_SM_PAIR_KEY_SZ_MIN) {
             res->sm_err = BLE_SM_ERR_ENC_KEY_SZ;
             res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_ENC_KEY_SZ);
+            res->enc_cb = 1;
         } else if (rsp->max_enc_key_size > BLE_SM_PAIR_KEY_SZ_MAX) {
             res->sm_err = BLE_SM_ERR_INVAL;
             res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_INVAL);
+            res->enc_cb = 1;
         } else if (MYNEWT_VAL(BLE_SM_SC_ONLY) && (rsp->max_enc_key_size != BLE_SM_PAIR_KEY_SZ_MAX)) {
             /* Fail if Secure Connections Only mode is on and remote does not meet
             * key size requirements - MITM was checked in last step
             */
             res->sm_err = BLE_SM_ERR_ENC_KEY_SZ;
             res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_ENC_KEY_SZ);
+            res->enc_cb = 1;
         } else if (!ble_sm_verify_auth_requirements(rsp->authreq)) {
             res->sm_err = BLE_SM_ERR_AUTHREQ;
             res->app_status = BLE_HS_SM_US_ERR(BLE_SM_ERR_AUTHREQ);
+            res->enc_cb = 1;
         } else {
             ble_sm_pair_cfg(proc);