ARM: dts: renesas: r8a7792: Add missing unit address to bus node

ARM: dts: renesas: r8a7792: Add missing unit address to bus node

Add missing unit address to bus node to fix the following DTC W=1
warning:

    arch/arm/boot/dts/renesas/r8a7792.dtsi:89.12-94.4: Warning (unit_address_vs_reg): /bus: node has a reg or ranges property, but no unit name

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260327234244.91707-4-marek.vasut+renesas@mailbox.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>