dinput: Convert keyboard buffer from internal data format to user data format

[Sergey Khodych]

> To reply to myself. I've missed the fact that if the requested format is 
> the
> same as Wine's internal format it will be a simple memcpy. I did not 
> want to
> penalize most dinput applications that just use default keyboard format 
> (array
> of 256 bytes).
> 
What do you think about using common buffer for all types of devices and 
translating a new event direct to user's data format? In this case we 
just copy buffer of base device.