arm64: dts: renesas: r8a779g0: Add MSIOF nodes

Add device nodes for the Clock-Synchronized Serial Interfaces with FIFO
(MSIOF) on the Renesas R-Car V4H (R8A779G0) SoC, including DMA support.

Based on patches in the BSP by Thanh Quan.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/450921ef6d8c30ca2953a1665c8597f6a69d01f2.1664204771.git.geert+renesas@glider.be