ASoC: rsnd: adg: Add per-SSI ADG and SSIF supply clock management

ASoC: rsnd: adg: Add per-SSI ADG and SSIF supply clock management

RZ/G3E's ADG module requires explicit clock management for SSI audio
interfaces that differs from R-Car Gen2/Gen3/Gen4:

 - Per-SSI ADG clocks (adg-ssi-N, or adg.ssi.N in legacy bindings)
   for each SSI module
 - A shared SSIF supply clock for the SSI subsystem

These clocks are acquired using optional APIs, making them transparent
to platforms that do not require them.

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/20260525110230.4014435-14-john.madieu.xa@bp.renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>