mtd: nand: mediatek: update DT bindings

Add MT2712 NAND Flash Controller dt bindings documentation.
Signed-off-by: NXiaolei Li <xiaolei.li@mediatek.com>
Reviewed-by: NMatthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>

Documentation/devicetree/bindings/mtd/mtk-nand.txt

@@ -12,7 +12,8 @@ tree nodes.
 
 The first part of NFC is NAND Controller Interface (NFI) HW.
 Required NFI properties:
-- compatible:			Should be "mediatek,mtxxxx-nfc".
+- compatible:			Should be one of "mediatek,mt2701-nfc",
+				"mediatek,mt2712-nfc".
 - reg:				Base physical address and size of NFI.
 - interrupts:			Interrupts of NFI.
 - clocks:			NFI required clocks.
@@ -141,7 +142,7 @@ Example:
 ==============
 
 Required BCH properties:
-- compatible:	Should be "mediatek,mtxxxx-ecc".
+- compatible:	Should be one of "mediatek,mt2701-ecc", "mediatek,mt2712-ecc".
 - reg:		Base physical address and size of ECC.
 - interrupts:	Interrupts of ECC.
 - clocks:	ECC required clocks.