Apply "u-boot-dont-touch-spi-nand" to ASUS RT-AX59U, ASUS TUF-AX4200 as
well as ASUS TUF-AX6000 routers to prevent U-Boot from wiping MTD
child nodes from DT.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
(cherry picked from commit 4387de94454913aa79bb88971eabcf1bfca78141)