ARM: dts: meson8b: add the PWM_D output pin

The PWM_D output is used for the VDDEE PWM regulator which supplies for
example the Mali GPU on the EC-100 and Odroid-C1 boards. Add the output
pin the VDDEE regulators can be added.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

arch/arm/boot/dts/meson8b.dtsi

@@ -361,6 +361,14 @@ mux {
 			};
 		};
 
+		pwm_d_pins: pwm-d {
+			mux {
+				groups = "pwm_d";
+				function = "pwm_d";
+				bias-disable;
+			};
+		};
+
 		uart_b0_pins: uart-b0 {
 			mux {
 				groups = "uart_tx_b0",