tty: riscom8, fix tty refcnt

Stanse found a tty refcnt leak on one fail path in rc_transmit.
Fix that by jumping to the 'out' label.

http://stanse.fi.muni.cz/



Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>