arm64: dts: renesas: r8a77965: m3nulcb: Initial device tree

Allow the bare M3-N-based ULCB board to boot.

Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>