um: remove dead code

GCC 4.6's -Wunused-but-set-variable found some dead code.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 35dd0b8..d51c404 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -176,10 +176,9 @@
 {
 	struct line *line = tty->driver_data;
 	unsigned long flags;
-	int err;
 
 	spin_lock_irqsave(&line->lock, flags);
-	err = flush_buffer(line);
+	flush_buffer(line);
 	spin_unlock_irqrestore(&line->lock, flags);
 }