Compression sync and data retrieval

[ooreilly]

The current design overloads the synchronization function, hipCompressSynchronize so that it takes on two responsibilities:

1. Synchronize the auxiliary stream
2. D2H Copy the compressed size and compute the compression ratio and return these values to the user.

A cleaner design would be to separate these two tasks into two functions:

1. hipCompressSynchronize(...) // Sync only
2. hipCompressGetCompressedSize(...) // Get data after sync