drm/i915/fbc: Finish polishing FBC1 registers

Switch all the FBC1 registers over to REG_BTT()/etc.
And while at it add a few more registers/bits that
escaped the net previously.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211104144520.22605-14-ville.syrjala@linux.intel.com


Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>