gpio: analogpin doesn't support write (that will come from pwm)

bbb.go

@@ -194,10 +194,6 @@ func (p *bbbAnalogPin) Read() (int, error) {
 	return strconv.Atoi(str)
 }
 
-func (p *bbbAnalogPin) Write(_ int) error {
-	return ErrFeatureNotImplemented
-}
-
 func (p *bbbAnalogPin) Close() error {
 	if !p.initialized {
 		return nil

gpio.go

@@ -54,9 +54,6 @@ type AnalogPin interface {
 	// N returns the logical GPIO number.
 	N() int
 
-	// Write writes the provided value to the pin.
-	Write(val int) error
-
 	// Read reads the value from the pin.
 	Read() (int, error)
 
@@ -172,16 +169,6 @@ func NewAnalogPin(key interface{}) (AnalogPin, error) {
 	return gpioDriverInstance.AnalogPin(key)
 }
 
-// AnalogWrite writes the provided value to the pin.
-func AnalogWrite(key interface{}, val int) error {
-	pin, err := NewAnalogPin(key)
-	if err != nil {
-		return err
-	}
-
-	return pin.Write(val)
-}
-
 // AnalogWrite reads a value from the pin.
 func AnalogRead(key interface{}) (int, error) {
 	pin, err := NewAnalogPin(key)