ASoC: topology: add private data to manifest

The topology file manifest should include a private data field. This
allows vendors to specify vendor data in the manifest, like
timestamps, hashes, additional information for removing platform
configuration out of drivers and making these configurable per platform

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>