dt-bindings: dma: fsl-mxs-dma: Add compatible string for i.MX8 chips

Add compatible string for all i.MX8 chips, which is backward compatible
with i.MX28. Set it to fall back to "fsl,imx28-dma-apbh".

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20250307215100.3257649-1-Frank.Li@nxp.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>