USB: legousbtower.c: remove a bogus NULL check

"udev" can't be NULL here.  The debugging printk() makes static checkers
complain when we dereference it later in the function inside the call to
usb_rcvctrlpipe().

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>