can: kvaser_usb: check number of channels returned by HW

commit 862474f8b46f6c1e600d4934e40ba40646c696ec upstream.

It is needed to check the number of channels returned by the HW because it
cannot be greater than MAX_NET_DEVICES otherwise it will crash.

Signed-off-by: Olivier Sobrie <olivier@sobrie.be>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>