TTY: ip22zilog, fix tty_flip_buffer_push call

This one was omitted by the "TTY: switch tty_flip_buffer_push" patch
because I did not compile-test mips driver. Now I do.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>