Input: fix potential overflows in driver/input/joystick

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/joystick/gf2k.c b/drivers/input/joystick/gf2k.c
index 8a3ad45..e4a699f 100644
--- a/drivers/input/joystick/gf2k.c
+++ b/drivers/input/joystick/gf2k.c
@@ -298,7 +298,7 @@
 	gameport_set_poll_handler(gameport, gf2k_poll);
 	gameport_set_poll_interval(gameport, 20);
 
-	sprintf(gf2k->phys, "%s/input0", gameport->phys);
+	snprintf(gf2k->phys, sizeof(gf2k->phys), "%s/input0", gameport->phys);
 
 	gf2k->length = gf2k_lens[gf2k->id];