arm64: dts: qcom: msm8976: Add and provide xo clk to rpmcc

In order for consumers of RPMCC XO clock to probe successfully
their parent needs to be feed with reference clock to obtain proper rate,
add fixed xo-board clock and supply it to rpmcc to make consumers happy.
Frequency setting is left per board basis just like on other recent trees.

Fixes: 0484d3ce ("arm64: dts: qcom: Add DTS for MSM8976 and MSM8956 SoCs")
Fixes: ff7f6d34 ("arm64: dts: qcom: Add support for SONY Xperia X/X Compact")
Signed-off-by: Adam Skladowski <a39.skl@gmail.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
[bjorn: Squashed the two patches]
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230302123051.12440-1-a39.skl@gmail.com
Link: https://lore.kernel.org/r/20230302123051.12440-2-a39.skl@gmail.com

arch/arm64/boot/dts/qcom/msm8956-sony-xperia-loire.dtsi

@@ -280,3 +280,7 @@ &usb_hs_phy {
 	vdda3p3-supply = <&pm8950_l13>;
 	status = "okay";
 };
+
+&xo_board {
+	clock-frequency = <19200000>;
+};

arch/arm64/boot/dts/qcom/msm8976.dtsi

@@ -20,6 +20,13 @@ / {
 
 	chosen { };
 
+	clocks {
+		xo_board: xo-board {
+			compatible = "fixed-clock";
+			#clock-cells = <0>;
+		};
+	};
+
 	cpus {
 		#address-cells = <1>;
 		#size-cells = <0>;
@@ -351,6 +358,8 @@ rpm_requests: rpm-requests {
 
 				rpmcc: clock-controller {
 					compatible = "qcom,rpmcc-msm8976", "qcom,rpmcc";
+					clocks = <&xo_board>;
+					clock-names = "xo";
 					#clock-cells = <1>;
 				};