riscv: configs: defconfig: Enable Renesas RZ/Five SoC

Enable Renesas RZ/Five SoC config in defconfig. It allows the default
upstream kernel to boot on RZ/Five SMARC EVK board.

Alongside enable SERIAL_SH_SCI config so that the serial driver used by
RZ/Five SoC is built-in.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20221028165921.94487-8-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>