drivers: tty: serial: sb1250-duart: fix formatting error

checkpatch complains:

    ERROR: space required before the open parenthesis '('
    torvalds#659: FILE: drivers/tty/serial/sb1250-duart.c:659:
    +	if(refcount_dec_and_test(&duart->map_guard))

Just add this missing space to make checkpatch happy.

Signed-off-by: Enrico Weigelt <info@metux.net>

drivers/tty/serial/sb1250-duart.c

@@ -656,7 +656,7 @@ static void sbd_release_port(struct uart_port *uport)
  iounmap(uport->membase);
  uport->membase = NULL;
 
- if(refcount_dec_and_test(&duart->map_guard))
+ if (refcount_dec_and_test(&duart->map_guard))
  release_mem_region(duart->mapctrl, DUART_CHANREG_SPACING);
  release_mem_region(uport->mapbase, uport->mapsize);
 }