serial: fix kernel-doc warnings in 8250.c

Fix kernel-doc warnings in drivers/tty/serial/8250/8250.c:

Warning(drivers/tty/serial/8250/8250.c:3128): No description found for parameter 'up'
Warning(drivers/tty/serial/8250/8250.c:3128): Excess function parameter 'port' description in 'serial8250_register_8250_port'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250.c

@@ -3113,7 +3113,7 @@ static struct uart_8250_port *serial8250_find_match_or_unused(struct uart_port *
 
 /**
  *	serial8250_register_8250_port - register a serial port
- *	@port: serial port template
+ *	@up: serial port template
  *
  *	Configure the serial port specified by the request. If the
  *	port exists and is in use, it is hung up and unregistered