transport/usb: Fix len comparison to allow fragmented acl

The comparison previously always triggered on the first fragment received
as the expected length (len) is always larger or equal to the total
received length (om_len). Partly addresses apache#940.

Author: ncasaril

nimble/transport/usb/src/ble_hci_usb.c

@@ -211,7 +211,7 @@ tud_bt_acl_data_received_cb(void *acl_data, uint16_t data_len)
     if (om->om_len > BLE_HCI_DATA_HDR_SZ) {
         data = incoming_acl_data->om_data;
         len = data[2] + (data[3] << 8) + BLE_HCI_DATA_HDR_SZ;
-        if (len >= incoming_acl_data->om_len) {
+        if (incoming_acl_data->om_len >= len) {
             incoming_acl_data = NULL;
             rc = ble_hci_usb_rx_acl_ll_cb(om, ble_hci_usb_rx_acl_ll_arg);
             (void)rc;