arm64: defconfig: Enable RZ_DMAC

Enable DMAC driver support for Renesas RZ/G2L based platforms.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20210920093605.8906-1-biju.das.jz@bp.renesas.com


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