ARM: dts: msm8974: Hook up adsp-pil's xo clock

Without this patch (and with CONFIG_QCOM_ADSP_PIL), I get this error:

	[    0.711529] qcom_adsp_pil adsp-pil: failed to get xo clock
	[    0.711540] remoteproc remoteproc0: releasing adsp-pil

With this patch, adsp-pil can initialize correctly.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>

arch/arm/boot/dts/qcom-msm8974.dtsi

@@ -250,6 +250,9 @@ adsp-pil {
 
 		cx-supply = <&pm8841_s2>;
 
+		clocks = <&xo_board>;
+		clock-names = "xo";
+
 		memory-region = <&adsp_region>;
 
 		qcom,smem-states = <&adsp_smp2p_out 0>;