drm/i915/dvo: Use REG_BIT() & co. for DVO registers

Polish the DVO port registers with REG_BIT()/etc.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221122120825.26338-8-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>