arm64: dts: renesas: r8a774a1: Fix hsusb reg size

HS-USB has registers outside the currently specified memory area,
therefore change the definition accordingly.

Fixes: ed898d4f ("arm64: dts: renesas: r8a774a1: Add USB-DMAC and HSUSB device nodes")
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-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>