ARM: dts: sun8i: r40: Add pinmux setting for CLK_OUT_A

CLK_OUT_A, an external clock output function driven from the clock
control unit, on the R40 is sometimes used to provide a low rate low
power clock to a WiFi or Bluetooth controller.

This patch adds a pinmux setting for it.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

arch/arm/boot/dts/sun8i-r40.dtsi

@@ -342,6 +342,11 @@ pio: pinctrl@1c20800 {
 			#interrupt-cells = <3>;
 			#gpio-cells = <3>;
 
+			clk_out_a_pin: clk-out-a-pin {
+				pins = "PI12";
+				function = "clk_out_a";
+			};
+
 			gmac_rgmii_pins: gmac-rgmii-pins {
 				pins = "PA0", "PA1", "PA2", "PA3",
 				       "PA4", "PA5", "PA6", "PA7",