dt-bindings: mtd: sunxi: Add H616 compatible

dt-bindings: mtd: sunxi: Add H616 compatible

The H616 NAND controller is quite different from the A10 and A23 ones,
some registers offset changed, and some new one are introduced.
Also, the DMA handling is different (it uses chained descriptors)

So, introduce a new compatible to represent this version of the IP.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Richard Genoud <richard.genoud@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>