can: usb: f81604: correctly anchor the urb in the read bulk callback

In the Linux kernel, the following vulnerability has been resolved:

can: usb: f81604: correctly anchor the urb in the read bulk callback

When submitting an urb, that is using the anchor pattern, it needs to be

anchored before submitting it otherwise it could be leaked if

usb_kill_anchored_urbs() is called. This logic is correctly done

elsewhere in the driver, except in the read bulk callback so do that

here also.