drm/i915: use ERR_CAST instead of ERR_PTR/PTR_ERR

Inspired by scripts/coccinelle/api/err_cast.cocci
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_drv.h

@@ -1419,7 +1419,7 @@ intel_atomic_get_crtc_state(struct drm_atomic_state *state,
 	struct drm_crtc_state *crtc_state;
 	crtc_state = drm_atomic_get_crtc_state(state, &crtc->base);
 	if (IS_ERR(crtc_state))
-		return ERR_PTR(PTR_ERR(crtc_state));
+		return ERR_CAST(crtc_state);
 
 	return to_intel_crtc_state(crtc_state);
 }