ARM: dts: r8a7745: Add HS-USB device node

From: Biju Das <biju.das@bp.renesas.com>

Define the R8A7745 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>
Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>