[PATCH] ppc32 CPM_UART: Fixed break send on SCC

SCC uart sends a break sequence each time it is stopped with the
CPM_CR_STOP_TX command. That means that each time an application closes the
serial device, a break is transmitted. To fix this, graceful tx stop is
issued for SCC.

Signed-off-by: David Jander <david.jander@protonic.nl>
Signed-off-by: Vitaly Bordug <vbordug@ru.mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>