drm/i915: Prepare clear color before wait_for_dependencies()

drm/i915: Prepare clear color before wait_for_dependencies()

Read out the clear color as soon as fences and the transient
data flush have finished. There is no need to wait for
all the display specific operations that might still be
going on. This could parallelize things a bit more effectively.

Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240930170415.23841-3-ville.syrjala@linux.intel.com