arm64: dts: medaitek: mt8395-nio-12l: Set i2c6 pins to bias-disable

GPIOs 25 and 26 do not support pull-up/pull-down when those are muxed
as I2C6's SDA6/SCL6 lines: set those to bias-disable to avoid warning
messages from the pinctrl driver.

Fixes: 96564b1e ("arm64: dts: mediatek: Introduce the MT8395 Radxa NIO 12L board")
Link: https://lore.kernel.org/r/20240409114211.310462-3-angelogioacchino.delregno@collabora.comSigned-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

arch/arm64/boot/dts/mediatek/mt8395-radxa-nio-12l.dts

@@ -528,7 +528,7 @@ i2c6_pins: i2c6-pins {
 		pins {
 			pinmux = <PINMUX_GPIO25__FUNC_SDA6>,
 				 <PINMUX_GPIO26__FUNC_SCL6>;
-			bias-pull-up = <MTK_PULL_SET_RSEL_111>;
+			bias-disable;
 		};
 	};