mediatek: define NMBM management region for WAX220

The NETGEAR WAX220 employs NMBM on SPI-NAND. In order to avoid dealing
with invalid factory data, enable NMBM in the area preceding the UBI
volume.

Signed-off-by: David Bauer <[email protected]>

target/linux/mediatek/dts/mt7986b-netgear-wax220.dts

@@ -186,6 +186,11 @@
 		spi-tx-buswidth = <4>;
 		spi-rx-buswidth = <4>;
 
+		mediatek,nmbm;
+		mediatek,bmt-max-ratio = <1>;
+		mediatek,bmt-max-reserved-blocks = <256>;
+		mediatek,bmt-remap-range = <0x0 0x580000>;
+
 		partitions: partitions {
 			#address-cells = <0x1>;
 			#size-cells = <0x1>;