arm64: dts: allwinner: a64: Add pinmux setting for CSI MCLK on PE1

Some camera modules have the SoC feeding a master clock to the sensor
instead of having a standalone crystal. This clock signal is generated
from the clock control unit and output from the CSI MCLK function of
pin PE1.

Add a pinmux setting for it for camera sensors to reference.
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi

@@ -595,6 +595,12 @@ csi_pins: csi-pins {
 				function = "csi";
 			};
 
+			/omit-if-no-ref/
+			csi_mclk_pin: csi-mclk-pin {
+				pins = "PE1";
+				function = "csi";
+			};
+
 			i2c0_pins: i2c0-pins {
 				pins = "PH0", "PH1";
 				function = "i2c0";