Add serial sound interface(SSIF-2) driver support for
RZ/G2L SoC.

Based on the work done by Chris Brandt for RZ/A SSI driver.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20210813091156.10700-2-biju.das.jz@bp.renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>