HID: magicmouse: Do not crash on missing msc->input

In the Linux kernel, the following vulnerability has been resolved: HID: magicmouse: Do not crash on missing msc->input Fake USB devices can send their own report descriptors for which the input_mapping() hook does not get called. In this case, msc->input stays NULL, leading to a crash at a later time. Detect this condition in the input_configured() hook and reject the device. This is not supposed to happen with actual magic mouse devices, but can be provoked by imposing as a magic mouse USB device.