samples: servo_motor: add HW PWM choice for NRF52 family

Hardware PWM make sense for servo control even in a sample,  add HW PWM
choice for NRF52 family, which support it.

Signed-off-by: Aaron Tsui <aaron.tsui@outlook.com>

samples/basic/servo_motor/src/main.c

@@ -17,9 +17,13 @@
 
 #if defined(CONFIG_SOC_QUARK_SE_C1000) || defined(CONFIG_SOC_QUARK_D2000)
 #define PWM_DEV CONFIG_PWM_QMSI_DEV_NAME
-#elif defined(CONFIG_PWM_NRF5_SW)
+#elif defined(CONFIG_SOC_FAMILY_NRF)
+#if defined(CONFIG_PWM_NRF5_SW)
 #define PWM_DEV CONFIG_PWM_NRF5_SW_0_DEV_NAME
 #else
+#define PWM_DEV DT_NORDIC_NRF_PWM_PWM_0_LABEL
+#endif  /* CONFIG_PWM_NRF5_SW */
+#else
 #error "Choose supported board or add new board for the application"
 #endif