Eevee: Fix T53413: Crash when using displacement bump relink.

ntree_shader_relink_displacement is creating a transient node that does not have a correct original to point to.
In this case we revert to constant uniform.

source/blender/gpu/intern/gpu_codegen.c

@@ -1589,6 +1589,15 @@ static GPUNodeLink *gpu_uniformbuffer_link(
         GPUMaterial *mat, bNode *node, GPUNodeStack *stack, const int index, const eNodeSocketInOut in_out)
 {
 	bNodeSocket *socket;
+
+	/* Some nodes can have been create on the fly and does
+	 * not have an original to point to. (i.e. the bump from
+	 * ntree_shader_relink_displacement). In this case just
+	 * revert to static constant folding. */
+	if (node->original == NULL) {
+		return NULL;
+	}
+
 	if (in_out == SOCK_IN) {
 		socket = BLI_findlink(&node->original->inputs, index);
 	}