PCI: rcar: Use gen2 fallback compatibility last

Improve readability by listing fallback compatibility strings after the
more-specific compatibility strings they provide a fallback for.

This does not affect run-time behaviour as it is the order in the DTB that
determines which compatibility string is used.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>