ARM: dts: qcom-apq8064: Set 'cxo_board' as ref clock of the DSI PHY

Add 'xo_board' as ref clock for the DSI PHY, it was previously
hardcoded in the PLL 'driver' for the 28nm 8960 PHY.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Andy Gross <agross@kernel.org>

arch/arm/boot/dts/qcom-apq8064.dtsi

@@ -1303,8 +1303,9 @@ dsi0_phy: dsi-phy@4700200 {
 				<0x04700300 0x200>,
 				<0x04700500 0x5c>;
 			reg-names = "dsi_pll", "dsi_phy", "dsi_phy_regulator";
-			clock-names = "iface_clk";
-			clocks = <&mmcc DSI_M_AHB_CLK>;
+			clock-names = "iface_clk", "ref";
+			clocks = <&mmcc DSI_M_AHB_CLK>,
+				 <&cxo_board>;
 		};