mediatek: drop NMBM layout for Xiaomi WR30U

This reverts commit dcdcfc1511.

This is a firmware for third-party u-boot mod, which should not
be carried here by us.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
(cherry picked from commit 1b7e62b20b)

target/linux/mediatek/dts/mt7981b-xiaomi-mi-router-wr30u-112m-nmbm.dts

@@ -1,22 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
-
-/dts-v1/;
-#include "mt7981b-xiaomi-mi-router-wr30u.dtsi"
-
-/ {
-	model = "Xiaomi Mi Router WR30U (112M UBI with NMBM-Enabled layout)";
-	compatible = "xiaomi,mi-router-wr30u-112m-nmbm", "mediatek,mt7981";
-};
-
-&spi_nand {
-	mediatek,nmbm;
-	mediatek,bmt-max-ratio = <1>;
-	mediatek,bmt-max-reserved-blocks = <64>;
-};
-
-&partitions {
-	partition@600000 {
-		label = "ubi";
-		reg = <0x600000 0x7000000>;
-	};
-};