arm64: dts: renesas: Add Renesas R8A77995 SoC support

Basic support for the R-Car D3 SoC:
  - PSCI,
  - CPU,
  - Cache controller,
  - Main clocks and controller,
  - Interrupt controller,
  - Timer,
  - Watchdog,
  - PMU,
  - Reset controller,
  - Product register,
  - System controller,
  - UART for console.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>