Supply 'super' for servo subclasses

Marlin/src/HAL/HAL_STM32/Servo.h

@@ -31,6 +31,7 @@ class libServo : public Servo {
     int8_t attach(const int pin, const int min, const int max);
     void move(const int value);
   private:
+    typedef Servo super;
     uint16_t min_ticks, max_ticks;
     uint8_t servoIndex;               // index into the channel data for this servo
 };

Marlin/src/HAL/HAL_STM32_F4_F7/Servo.h

@@ -35,6 +35,7 @@ class libServo : public Servo {
     int8_t attach(const int pin, const int min, const int max);
     void move(const int value);
   private:
+    typedef Servo super;
     uint16_t min_ticks, max_ticks;
     uint8_t servoIndex;               // index into the channel data for this servo
 };

Marlin/src/HAL/HAL_TEENSY31_32/Servo.h

@@ -30,7 +30,8 @@ class libServo : public Servo {
     int8_t attach(const int pin, const int min, const int max);
     void move(const int value);
   private:
-     uint16_t min_ticks;
-     uint16_t max_ticks;
-     uint8_t servoIndex;               // index into the channel data for this servo
+    typedef Servo super;
+    uint16_t min_ticks;
+    uint16_t max_ticks;
+    uint8_t servoIndex;               // index into the channel data for this servo
 };

Marlin/src/HAL/HAL_TEENSY35_36/Servo.h

@@ -30,7 +30,8 @@ class libServo : public Servo {
     int8_t attach(const int pin, const int min, const int max);
     void move(const int value);
   private:
-     uint16_t min_ticks;
-     uint16_t max_ticks;
-     uint8_t servoIndex; // Index into the channel data for this servo
+    typedef Servo super;
+    uint16_t min_ticks;
+    uint16_t max_ticks;
+    uint8_t servoIndex; // Index into the channel data for this servo
 };