PCI: aardvark: Use dev_fwnode() instead of of_node_to_fwnode(dev->of_node)

Use simple
  dev_fwnode(dev)
instead of
  struct device_node *node = dev->of_node;
  of_node_to_fwnode(node)
especially since the node variable is not used elsewhere in the function.

Link: https://lore.kernel.org/r/20220110015018.26359-9-kabel@kernel.org
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>