This PHY is  still  mostly undocumented --  the only documented registers
exist on R-Car V3H (R8A77980) SoC.  Add the corresponding device tree
bindings.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>