of/address: use atomic allocation in pci_register_io_range()

When kzalloc() is called under spin_lock(), GFP_ATOMIC should be
used to avoid sleeping allocation.
The call tree is:
  of_pci_range_to_resource()
    --> pci_register_io_range() <-- takes spin_lock(&io_range_lock);
       --> kzalloc()
Signed-off-by: Jingoo Han <jingoohan1@gmail.com>
Cc: stable@vger.kernel.org # 3.18+
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/address.c

@@ -712,7 +712,7 @@ int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size)
 	}
 
 	/* add the range to the list */
-	range = kzalloc(sizeof(*range), GFP_KERNEL);
+	range = kzalloc(sizeof(*range), GFP_ATOMIC);
 	if (!range) {
 		err = -ENOMEM;
 		goto end_register;