MAINTAINERS: Add entry for Renesas RZ ASoC driver

Add a new entry to the MAINTAINERS file for Renesas RZ ASoC driver.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://patch.msgid.link/20241025150511.722040-6-prabhakar.mahadev-lad.rj@bp.renesas.com


Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>