arm: dts: mediatek: disable fan node for mt7987

There's no fan in MedisTek's reference design. Disable it for now.

diff --git a/arch/arm/dts/mt7987a.dtsi b/arch/arm/dts/mt7987a.dtsi
index bf53e89..365fefd 100644
--- a/arch/arm/dts/mt7987a.dtsi
+++ b/arch/arm/dts/mt7987a.dtsi
@@ -29,7 +29,7 @@
 
 &fan {
 	pwms = <&pwm 0 50000 0>;
-	status = "okay";
+	status = "disabled";
 };
 
 &i2c0 {