Revert "can: kvaser_usb: free buf in error paths"

This reverts commit 70d9dccf which was
commit 435019b4 upstream.

Jimmy Assarsson asks that it be reverted as it's not correct there.

Reported-by: Jimmy Assarsson <jimmyassarsson@gmail.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>