Add both some new and some old fields to child device config
parameters. Prepare for switching to just one child device config. Use
naming from struct old_child_dev_config for common fields.

No functional changes.

Cc: Animesh Manna <animesh.manna@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/bbf66c934eb5c655fd7dda6c1bb8f218c8edc209.1503600621.git.jani.nikula@intel.com