[PATCH 0/1] MR2120: user32: Post WM_INPUT_DEVICE_CHANGE when registering for notifications

[Evan Tang (＠etang-cw)]

This seems to be relied on by some versions of [this Unreal Engine input plugin](https://www.unrealengine.com/marketplace/en-US/product/wm-input-manager)

Note: I'm not sure how to deal with `HID_USAGE_GENERIC_KEYPAD`, which (I think) would fall under `RIM_TYPEKEYBOARD`.  Do we need to store extra info to differentiate these from `HID_USAGE_GENERIC_KEYBOARD` or is there something in the device info struct that can differentiate them?