Resolve "PWM-locked" / "phase-locked" waveform merge leftover in Servo lib (#7978)

Library was overlooked in "PWM-locked" / "phase-locked" waveform mode merge.

Author: dok-net

cores/esp8266/core_esp8266_waveform_pwm.cpp

@@ -356,7 +356,7 @@ int startWaveformClockCycles_weak(uint8_t pin, uint32_t timeHighCycles, uint32_t
   (void) phaseOffsetUS;
   (void) autoPwm;
 
-   if ((pin > 16) || isFlashInterfacePin(pin)) {
+   if ((pin > 16) || isFlashInterfacePin(pin) || (timeHighCycles == 0)) {
     return false;
   }
   Waveform *wave = &wvfState.waveform[pin];

libraries/Servo/src/Servo.cpp

@@ -69,13 +69,8 @@ uint8_t Servo::attach(int pin, uint16_t minUs, uint16_t maxUs)
 uint8_t Servo::attach(int pin, uint16_t minUs, uint16_t maxUs, int value)
 {
   if (!_attached) {
-#ifdef WAVEFORM_LOCKED_PHASE
     pinMode(pin, OUTPUT);
     digitalWrite(pin, LOW);
-#else
-    digitalWrite(pin, LOW);
-    pinMode(pin, OUTPUT);
-#endif
     _pin = pin;
     _attached = true;
   }
@@ -95,11 +90,7 @@ void Servo::detach()
 {
   if (_attached) {
     _servoMap &= ~(1 << _pin);
-#ifdef WAVEFORM_LOCKED_PHASE
     startWaveform(_pin, 0, REFRESH_INTERVAL, 1);
-#else
-    // TODO - timeHigh == 0 is illegal in _PWM code branch.  Do nothing for now.
-#endif
     delay(REFRESH_INTERVAL / 1000); // long enough to complete active period under all circumstances.
     stopWaveform(_pin);
     _attached = false;
@@ -124,13 +115,9 @@ void Servo::writeMicroseconds(int value)
   _valueUs = value;
   if (_attached) {
     _servoMap &= ~(1 << _pin);
-#ifdef WAVEFORM_LOCKED_PHASE
     // Find the first GPIO being generated by checking GCC's find-first-set (returns 1 + the bit of the first 1 in an int32_t)
     int phaseReference = __builtin_ffs(_servoMap) - 1;
     if (startWaveform(_pin, _valueUs, REFRESH_INTERVAL - _valueUs, 0, phaseReference))
-#else
-    if (startWaveform(_pin, _valueUs, REFRESH_INTERVAL - _valueUs, 0))
-#endif
     {
       _servoMap |= (1 << _pin);
     }