Input: db9 - clear unused function pointers

db9_parport_cb is a local uninitialized structure and the member
function pointers will be pointing to arbitrary locations unless they
are cleared.

Fixes: 2260c419b52b ("Input: db9 - use parallel port device model")
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/joystick/db9.c

@@ -592,6 +592,7 @@ static void db9_attach(struct parport *pp)
 		return;
 	}
 
+	memset(&db9_parport_cb, 0, sizeof(db9_parport_cb));
 	db9_parport_cb.flags = PARPORT_FLAG_EXCL;
 
 	pd = parport_register_dev_model(pp, "db9", &db9_parport_cb, port_idx);