ASoC: Intel: Skylake: Fix to parse consecutive string tkns in manifest

Element size in the manifest should be updated for each token, so that the
loop can parse all the string elements in the manifest. This was not
happening when more than two string elements appear consecutively, as it is
not updated with correct string element size. Fixed with this patch.

Signed-off-by: Shreyas NC <shreyas.nc@intel.com>
Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>