drm/i915: Calculate a new pipe_config based on new enabled state

With the current implementation of intel_modeset_affected_pipes(), if a
pipe will be enabled then it is in modeset_pipes. We'll remove that mask
in a follow up patch, but want to preserve this behavior, so just make
that explicit.
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -12220,7 +12220,7 @@ intel_modeset_compute_config(struct drm_crtc *crtc,
 	if (IS_ERR(pipe_config))
 		return pipe_config;
 
-	if (!(*modeset_pipes & (1 << to_intel_crtc(crtc)->pipe)))
+	if (!pipe_config->base.enable)
 		return pipe_config;
 
 	ret = intel_modeset_pipe_config(crtc, mode, state, pipe_config);