dt-bindings: usb: renesas_usbhs: convert bindings to json-schema

Convert Renesas USBHS (HS-USB) controller bindings documentation
to json-schema.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1573102944-11095-1-git-send-email-yoshihiro.shimoda.uh@renesas.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>