serial: uartps: Remove useless return from cdns_uart_poll_put_char

There is no reason to call return at the end of function which should
return void.

The patch is also remove one checkpatch warning:
WARNING: void function return statements are not generally useful
+	return;
+}

Fixes: 6ee04c6c54 ("tty: xuartps: Add polled mode support for xuartps")
Signed-off-by: Nava kishore Manne <nava.manne@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/xilinx_uartps.c

@@ -1079,8 +1079,6 @@ static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
 		cpu_relax();
 
 	spin_unlock_irqrestore(&port->lock, flags);
-
-	return;
 }
 #endif