ARM: dts: r8a7743: Add HS-USB device node

Define the R8A7743 generic part of the HS-USB device node. It is up to the
board file to enable the device.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Signed-off-by: Chris Paterson <chris.paterson2@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>