whether there is space in transmitter hold register.

So switch UART_LSR_TEMT to UART_LSR_THRE in that specific case according
to the change in 1.14 moxa drivers.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>