Fix more gosec G104 warnings

I have a hard time running it locally, so testing in prod.

experimental/devices/epd/epd.go

@@ -372,9 +372,9 @@ func (d *Dev) Init() error {
 
 // Reset can be also used to awaken the device
 func (d *Dev) Reset() {
-	d.rst.Out(gpio.Low)
+	_ = d.rst.Out(gpio.Low)
 	time.Sleep(200 * time.Millisecond)
-	d.rst.Out(gpio.High)
+	_ = d.rst.Out(gpio.High)
 	time.Sleep(200 * time.Millisecond)
 }
 

experimental/devices/mcp23xxx/mcp23xxx.go

@@ -107,7 +107,8 @@ func makeDev(ra registerAccess, variant Variant, devicename string) (*Dev, error
 		}
 		pins[i] = ports[i].pins()
 		for _, pin := range pins[i] {
-			gpioreg.Register(pin)
+			// Ignore registration failure.
+			_ = gpioreg.Register(pin)
 		}
 	}
 	return &Dev{