🐛 Fix, improve PWM on AVR (#23463)

Marlin/src/HAL/AVR/HAL.h

@@ -207,6 +207,7 @@ inline void HAL_adc_init() {
 #define strtof strtod
 
 #define HAL_CAN_SET_PWM_FREQ   // This HAL supports PWM Frequency adjustment
+#define PWM_FREQUENCY 1000     // Default PWM frequency when set_pwm_duty() is called without set_pwm_frequency()
 
 /**
  *  set_pwm_frequency
@@ -226,3 +227,9 @@ void set_pwm_frequency(const pin_t pin, const uint16_t f_desired);
  *  Optionally allows changing the maximum size of the provided value to enable finer PWM duty control [default = 255]
  */
 void set_pwm_duty(const pin_t pin, const uint16_t v, const uint16_t v_size=255, const bool invert=false);
+
+/*
+ * init_pwm_timers
+ * sets the default frequency for timers 2-5 to 1000HZ
+ */
+void init_pwm_timers();