USB: microtek: fix info-leak at probe

Add missing bulk-in endpoint sanity check to prevent uninitialised stack
data from being reported to the system log and used as endpoint
addresses.

Fixes: 1da177e4

 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Reported-by:  <syzbot+5630ca7c3b2be5c9da5e@syzkaller.appspotmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20191003070931.17009-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>