interconnect: imx: Remove a useless test

'dn' can't be NULL here, it is tested just the line above.
Remove this useless test.

Signed-off-by: Christophe JAILLET <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Georgi Djakov <[e-mail]>

drivers/interconnect/imx/imx.c

···
 			return -ENODEV;
 		}
 		/* Allow scaling to be disabled on a per-node basis */
-		if (!dn || !of_device_is_available(dn)) {
+		if (!of_device_is_available(dn)) {
 			dev_warn(dev, "Missing property %s, skip scaling %s\n",
 				 adj->phandle_name, node->name);
 			of_node_put(dn);