arm64: dts: renesas: r8a779g0: Add CAN-FD node

Add device nodes for the CAN-FD interface and the related external CAN
clock on the Renesas R-Car V4H (R8A779G0) SoC.

Based on a patch in the BSP by Kazuya Mizuguch.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/6c55d0995089917216ee261a8b8cbb980c7b5304.1674500205.git.geert+renesas@glider.be