dt-bindings: dma: renesas,rz-dmac: document RZ/{T2H,N2H}

dt-bindings: dma: renesas,rz-dmac: document RZ/{T2H,N2H}

The Renesas RZ/T2H (R9A09G077) and RZ/N2H (R9A09G087) SoCs have three
DMAC instances. Compared to the previously supported RZ/V2H, these SoCs
are missing the error interrupt line and the reset lines, and they use
a different ICU IP.

Document them, and use RZ/T2H as a fallback for RZ/N2H as the DMACs are
entirely compatible.

Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260105114445.878262-4-cosmin-gabriel.tanislav.xa@renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>