Currently we can parse a single manifest data block. But manifest
private data can have multiple data blocks.

So, fix the parsing logic to parse multiple data blocks by returning
offset of each parsed data block.
Signed-off-by: NShreyas NC <shreyas.nc@intel.com>
Signed-off-by: NGuneshwor Singh <guneshwor.o.singh@intel.com>
Acked-By: NVinod Koul <vinod.koul@intel.com>
Signed-off-by: NMark Brown <broonie@kernel.org>