can: kvaser_usb: kvaser_usb_leaf: Fix some info-leaks to USB devices

Uninitialized Kernel memory can leak to USB devices.

Fix this by using kzalloc() instead of kmalloc().

Signed-off-by: Xiaolong Huang <butterflyhuangxx@gmail.com>
Fixes: 7259124eac7d ("can: kvaser_usb: Split driver into kvaser_usb_core.c and kvaser_usb_leaf.c")
Cc: linux-stable <stable@vger.kernel.org> # >= v4.19
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
