arm64: defconfig: renesas: Enable Renesas r8a7795 SoC

This patch enables the Renesas R-Car H3 SoC together with the
SCIF driver in the arm64 defconfig.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>