[4/14]hid: Implement HidP_GetCaps

[Vincent Povirk]

> Most likely you should not be sharing them. Why do you need this?

Best I can tell, this is how MS designed it. The _HIDP_PREPARSED_DATA
structure can be obtained through ioctl or passed to certain hid.dll
functions to carry information about the device. However, the details
of that structure are not documented, and MSDN makes it sound like it
can change between Windows versions.