Pull the VLV/CHV DPIO PHY sideband registers to their own file.

v2: drop stray tabs (Jani)
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240422083457.23815-15-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>