Fix pin configuration in NewSPI function

Author: ysoldak

ssd1306/ssd1306_spi.go

@@ -19,9 +19,9 @@ type SPIBus struct {
 // NewSPI creates a new SSD1306 connection. The SPI wire must already be configured.
 func NewSPI(bus drivers.SPI, dcPin, resetPin, csPin pin.Output) *Device {
 	// configure GPIO pins (on baremetal targets only, for backwards compatibility)
-	legacy.ConfigurePinOut(b.dcPin)
-	legacy.ConfigurePinOut(b.resetPin)
-	legacy.ConfigurePinOut(b.csPin)
+	legacy.ConfigurePinOut(dcPin)
+	legacy.ConfigurePinOut(resetPin)
+	legacy.ConfigurePinOut(csPin)
 	return &Device{
 		bus: &SPIBus{
 			wire:     bus,