drm/i915: Fix up skl_program_plane() pxp stuff

drm/i915: Fix up skl_program_plane() pxp stuff

There's lots of expensive stuff inserted between the PLANE_CTL
and  PLANE_SURF writes even though the comment before the PLANE_CTL
write says not to put stuff there. Move it all to a more apporiate
place.

There's also a weird PLANE_COLOR_CTL RMW in there. I guess because
force_black was computed way too late originally, but that is now
sorted.

Cc: Anshuman Gupta <anshuman.gupta@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Juston Li <juston.li@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211006235704.28894-3-ville.syrjala@linux.intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>