can: kvaser_usb: Remove unused commands and defines

Remove unused commands:
  struct kvaser_msg_cardinfo2
  struct leaf_msg_tx_acknowledge
  struct usbcan_msg_tx_acknowledge

Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>