PCI: mvebu: Use for_each_available_child_of_node() to walk child nodes
Rather than using for_each_child_of_node() and testing each child's
availability, use the for_each_available_child_of_node() helper instead.
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> (Armada XP GP) Tested-by: Andrew Lunn <andrew@lunn.ch> (Kirkwood DIR665) Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>