Gets virtual disk block size in sectors.
PRL_RESULT PrlDiskParams_GetBlockSize( PRL_HANDLE hParams, PRL_UINT32_PTR pnSize );
PrlDisk.h
PRL_RESULT. Possible values are:
PRL_ERR_INVALID_ARG - Invalid handle or null pointer was passed. PRL_ERR_SUCCESS - Function completed successfully.
(aligned to track, track = CHSsectors * sector_size)