drm/i915/fbc: Clear frontbuffer busy bits on flip

We are planning to move flush performed from work queue. This
means it is possible to have invalidate -> flip -> flush sequence.
Handle this by clearing possible busy bits on flip.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230901093500.3463046-2-jouni.hogander@intel.com

drivers/gpu/drm/i915/display/intel_fbc.c

@@ -1307,11 +1307,9 @@ static void __intel_fbc_post_update(struct intel_fbc *fbc)
 	lockdep_assert_held(&fbc->lock);
 
 	fbc->flip_pending = false;
+	fbc->busy_bits = 0;
 
-	if (!fbc->busy_bits)
-		intel_fbc_activate(fbc);
-	else
-		intel_fbc_deactivate(fbc, "frontbuffer write");
+	intel_fbc_activate(fbc);
 }
 
 void intel_fbc_post_update(struct intel_atomic_state *state,