waveshare213v2: Move command and data sending code into error handler

This code isn't used directly and there's no need to keep the additional
complexity.

Signed-off-by: Michael Hanselmann <public@hansmi.ch>

waveshare2in13v2/errorhandler.go

@@ -44,12 +44,20 @@ func (eh *errorHandler) sendCommand(cmd byte) {
 	if eh.err != nil {
 		return
 	}
-	eh.err = eh.d.sendCommand(cmd)
+
+	eh.dcOut(gpio.Low)
+	eh.csOut(gpio.Low)
+	eh.cTx([]byte{cmd}, nil)
+	eh.csOut(gpio.High)
 }
 
-func (eh *errorHandler) sendData(d []byte) {
+func (eh *errorHandler) sendData(data []byte) {
 	if eh.err != nil {
 		return
 	}
-	eh.err = eh.d.sendData(d)
+
+	eh.dcOut(gpio.High)
+	eh.csOut(gpio.Low)
+	eh.cTx(data, nil)
+	eh.csOut(gpio.High)
 }

waveshare2in13v2/waveshare213v2.go

@@ -357,28 +357,6 @@ func (d *Dev) String() string {
 	return fmt.Sprintf("epd.Dev{%s, %s, Height: %d, Width: %d}", d.c, d.dc, d.opts.Height, d.opts.Width)
 }
 
-func (d *Dev) sendData(c []byte) error {
-	eh := errorHandler{d: *d}
-
-	eh.dcOut(gpio.High)
-	eh.csOut(gpio.Low)
-	eh.cTx(c, nil)
-	eh.csOut(gpio.High)
-
-	return eh.err
-}
-
-func (d *Dev) sendCommand(cmd byte) error {
-	eh := errorHandler{d: *d}
-
-	eh.dcOut(gpio.Low)
-	eh.csOut(gpio.Low)
-	eh.cTx([]byte{cmd}, nil)
-	eh.csOut(gpio.High)
-
-	return eh.err
-}
-
 func (d *Dev) turnOnDisplay() error {
 	eh := errorHandler{d: *d}