ARM: dts: koelsch: Correct clock frequency of X2 DU clock input

The X2 crystal oscillator on the Koelsch development board provides a
74.25 MHz clock, not a 148.5 MHz clock.

Fixes: cd21cb46 ("ARM: shmobile: koelsch: Add DU external pixel clocks to DT")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7791-koelsch.dts

@@ -292,7 +292,7 @@ hdmi_con_out: endpoint {
 	x2_clk: x2-clock {
 		compatible = "fixed-clock";
 		#clock-cells = <0>;
-		clock-frequency = <148500000>;
+		clock-frequency = <74250000>;
 	};
 
 	x13_clk: x13-clock {