USB: io_ti.c: remove unneeded null tty check

The Coverity checker (and Adrian Bunk) spotted an inconsistent NULL check of
port->tty (it's blindly dereferenced later without the check).

Alan Cox confirmed the check can go.
Signed-off-by: NRay Lee <ray-lk@madrabbit.org>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/io_ti.c

@@ -1941,8 +1941,7 @@ static int edge_open (struct usb_serial_port *port, struct file * filp)
 	if (edge_port == NULL)
 		return -ENODEV;
 
-	if (port->tty)
-		port->tty->low_latency = low_latency;
+	port->tty->low_latency = low_latency;
 
 	port_number = port->number - port->serial->minor;
 	switch (port_number) {