arm64: dts: renesas: beacon: Enable SPI

The baseboard routes the SPI to a header which can/will be configured at
either the kit level or using device tree overlays.  Because the baseboard
be supporting more than one kit, enable at the baseboard level rather
than a bunch of duplicates later.

Signed-off-by: Adam Ford <aford173@gmail.com>
Link: https://lore.kernel.org/r/20201213183759.223246-14-aford173@gmail.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>