ASoC: hdac_hdmi: parse eld for channel map capability

This patch parses ELD speaker allocation data block to find
sink's chmap capability.

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