tests: drivers: pwm: Add pwm_api overlay and update yaml file

This commit adds the pwm overlay file for the brd4342a board,
enabling pwm support and also updates the pwm tag in
siwx917_dk2605a.yaml.

Upstream-status: available
Signed-off-by: S Mohamed Fiaz <[email protected]>
(cherry picked from commit c8fa6c8)

Author: fimohame

boards/silabs/dev_kits/siwx917_dk2605a/siwx917_dk2605a.yaml

@@ -22,4 +22,5 @@ supported:
   - wifi
   - rtc
   - counter
+  - pwm
 vendor: silabs

tests/drivers/pwm/pwm_api/boards/siwx917_rb4342a.overlay

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2025 Silicon Laboratories Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/dt-bindings/pwm/pwm.h>
+
+/ {
+	aliases {
+		pwm-test = &pwm;
+	};
+};
+
+&pinctrl0 {
+	pwm_ch: pwm_ch {
+		group1 {
+			pinmux = <PWM_0H_HP7>; /* GPIO_7 P20 */
+		};
+	};
+};
+
+&pwm {
+	pinctrl-0 = <&pwm_ch>;
+	pinctrl-names = "default";
+
+	pwm_channel1: pwm_channel1 {
+		pwms = <&pwm 0 1000000>;
+	};
+	silabs,pwm-polarity = <PWM_POLARITY_NORMAL>;
+	status = "okay";
+};