arm64: dts: qcom: msm8994: don't use underscore in node name

We have underscore (_) in node name leading to warning:
arch/arm64/boot/dts/qcom/msm8994-msft-lumia-octagon-cityman.dt.yaml: clocks: xo_board: {'type': 'object'} is not allowed for {'compatible': ['fixed-clock'], '#clock-cells': [[0]], 'clock-frequency': [[19200000]], 'phandle': [[26]]}
arch/arm64/boot/dts/qcom/msm8994-msft-lumia-octagon-cityman.dt.yaml: clocks: sleep_clk: {'type': 'object'} is not allowed for {'compatible': ['fixed-clock'], '#clock-cells': [[0]], 'clock-frequency': [[32768]]}

Fix this by changing node name to use dash (-)
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20210308060826.3074234-9-vkoul@kernel.org
[bjorn: Added clock-output-names to satisfy parent_names]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

arch/arm64/boot/dts/qcom/msm8994.dtsi

@@ -15,16 +15,18 @@ / {
 	chosen { };
 
 	clocks {
-		xo_board: xo_board {
+		xo_board: xo-board {
 			compatible = "fixed-clock";
 			#clock-cells = <0>;
 			clock-frequency = <19200000>;
+			clock-output-names = "xo_board";
 		};
 
-		sleep_clk: sleep_clk {
+		sleep_clk: sleep-clk {
 			compatible = "fixed-clock";
 			#clock-cells = <0>;
 			clock-frequency = <32768>;
+			clock-output-names = "sleep_clk";
 		};
 	};