Extract the BXT/GLK DPIO PHY register definitions into their own file.

v2: Adjust gvt accordingly
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240417151232.32175-1-ville.syrjala@linux.intel.com