arm64: dts: renesas: draak: Add RPC HyperFlash device node

Add the RPC HyperFlash device node along with its partitions to the
common Draak board DTS file.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/0f3d3018ecfcdce1bce67708708a6d3a98368b10.1648548339.git.geert+renesas@glider.be