arm64: dts: rockchip: Fix bluetooth properties on Rock960 boards

The expected clock-name is different, and extclk also is deprecated
in favor of txco for clocks that are not crystals.

So fix it to match the binding.

Fixes: c72235c ("arm64: dts: rockchip: Add on-board WiFi/BT support for Rock960 boards")
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20241008203940.2573684-5-heiko@sntech.de
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: mmind

arch/arm64/boot/dts/rockchip/rk3399-rock960.dtsi

@@ -576,7 +576,7 @@
 	bluetooth {
 		compatible = "brcm,bcm43438-bt";
 		clocks = <&rk808 1>;
-		clock-names = "ext_clock";
+		clock-names = "txco";
 		device-wakeup-gpios = <&gpio2 RK_PD3 GPIO_ACTIVE_HIGH>;
 		host-wakeup-gpios = <&gpio0 RK_PA4 GPIO_ACTIVE_HIGH>;
 		shutdown-gpios = <&gpio0 RK_PB1 GPIO_ACTIVE_HIGH>;