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: NSimon Horman <horms+renesas@verge.net.au>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NRob Herring <robh@kernel.org>