arm64: dts: renesas: r8a779f0: Add L3 cache controller

Describe the cache configuration for the first Cortex-A55 CPU core on
the Renesas R-Car S4-8 (R8A779F0) SoC.

Extracted from a larger patch in the BSP by LUU HOAI.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/a63715ce1d2d2fcc7ab987f7a1b40847965e8d6a.1654701480.git.geert+renesas@glider.be