riscv: dts: sophgo: disable write-protection for milkv duo

Milkv Duo does not have a write-protect pin, so disable write protect
to prevent SDcards misdetected as read-only.

Fixes: 89a7056e ("riscv: dts: sophgo: add sdcard support for milkv duo")
Signed-off-by: Haylen Chu <heylenay@outlook.com>
Link: https://lore.kernel.org/r/SEYPR01MB4221943C7B101DD2318DA0D3D7CE2@SEYPR01MB4221.apcprd01.prod.exchangelabs.comSigned-off-by: Inochi Amaoto <inochiama@outlook.com>
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>

arch/riscv/boot/dts/sophgo/cv1800b-milkv-duo.dts

@@ -45,6 +45,7 @@ &sdhci0 {
 	no-1-8-v;
 	no-mmc;
 	no-sdio;
+	disable-wp;
 };
 
 &uart0 {