Input: fix potential overflows in driver/input/touchscreen

Change all sprintfs into snprintfs to make sure we won't stomp on
data adjacent to our buffers.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/touchscreen/mtouch.c b/drivers/input/touchscreen/mtouch.c
index 1d0d37e..8647a90 100644
--- a/drivers/input/touchscreen/mtouch.c
+++ b/drivers/input/touchscreen/mtouch.c
@@ -143,7 +143,7 @@
 
 	mtouch->serio = serio;
 	mtouch->dev = input_dev;
-	sprintf(mtouch->phys, "%s/input0", serio->phys);
+	snprintf(mtouch->phys, sizeof(mtouch->phys), "%s/input0", serio->phys);
 
 	input_dev->private = mtouch;
 	input_dev->name = "MicroTouch Serial TouchScreen";