nozomi: don't use flush_scheduled_work()

flush_scheduled_work() in tty_exit() doesn't seem to target any
specific work.  If it was to flush work items used in tty generic
layer, they're already flushed properly during tty release.

flush_scheduled_work() is going away.  Remove the seemingly redundant
usage.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>