ASoC: Intel: Skylake: Parse multiple manifest data blocks

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: Shreyas NC <shreyas.nc@intel.com>
Signed-off-by: Guneshwor Singh <guneshwor.o.singh@intel.com>
Acked-By: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>