Device events now use uint32 for hw_code and modifiers in the IPC

Device events now use uint32 for hw_code and modifiers in the IPC

Changed device event IPC to use uint32 for hw_code and modifiers, to be
more consistent with the rest of the API.
Kept AT-SPI struct using gushorts to avoid ABI break, and the registry daemon
will continue to accept the old API as well as the new for now.