drm/i915: Use _MMIO_TRANS2() where appropriate

Stop hand rolling _MMIO_TRANS2() and just use the real thing.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220623130900.26078-7-ville.syrjala@linux.intel.com


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