samples: blinky_pwm: Use nRF SW PWM driver on nRF DKs

The default nRF hardware PWM driver is not very suitable for this
sample as that driver does not allow setting a period longer than
~262 ms. Use the nRF SW PWM driver instead. This will also ensure
that the driver is built by CI for nRF52, nRF53, and nRF91 Series.

Signed-off-by: Andrzej Głąbek <[email protected]>

Author: anangl

samples/basic/blinky_pwm/boards/nrf52840dk_nrf52840.overlay

@@ -0,0 +1,12 @@
+&pwm0 {
+	status = "disabled";
+};
+
+&sw_pwm {
+	status = "okay";
+	channel-gpios = <&gpio0 13 PWM_POLARITY_INVERTED>;
+};
+
+&pwm_led0 {
+	pwms = <&sw_pwm 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
+};

samples/basic/blinky_pwm/boards/nrf5340dk_nrf5340_cpuapp.overlay

@@ -0,0 +1,12 @@
+&pwm0 {
+	status = "disabled";
+};
+
+&sw_pwm {
+	status = "okay";
+	channel-gpios = <&gpio0 28 PWM_POLARITY_INVERTED>;
+};
+
+&pwm_led0 {
+	pwms = <&sw_pwm 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
+};

samples/basic/blinky_pwm/boards/nrf9160dk_nrf9160.overlay

@@ -0,0 +1,12 @@
+&pwm0 {
+	status = "disabled";
+};
+
+&sw_pwm {
+	status = "okay";
+	channel-gpios = <&gpio0 2 PWM_POLARITY_INVERTED>;
+};
+
+&pwm_led0 {
+	pwms = <&sw_pwm 0 PWM_MSEC(20) PWM_POLARITY_INVERTED>;
+};