arm64: dts: qcom: sm8250: correct sdhc_2 xo clk

sdhc_2 uses 19200000 Hz clock rather than wrongly specified xo_board
(39400000 Hz). Specify correct clock to fix DLL setup for SDR104 mode.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Fixes: c4cf0300 ("arm64: dts: qcom: sm8250: Add support for SDC2")
Link: https://lore.kernel.org/r/20210109011252.3436533-1-dmitry.baryshkov@linaro.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

arch/arm64/boot/dts/qcom/sm8250.dtsi

@@ -1825,7 +1825,7 @@ sdhc_2: sdhci@8804000 {
 
 			clocks = <&gcc GCC_SDCC2_AHB_CLK>,
 				 <&gcc GCC_SDCC2_APPS_CLK>,
-				 <&xo_board>;
+				 <&rpmhcc RPMH_CXO_CLK>;
 			clock-names = "iface", "core", "xo";
 			iommus = <&apps_smmu 0x4a0 0x0>;
 			qcom,dll-config = <0x0007642c>;