Add fallback compatibility string for R-Car Gen 2 family.  This is in
keeping with the fallback scheme being adopted wherever appropriate for
drivers for Renesas SoCs.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rob Herring <robh@kernel.org>