Calling digitalRead() should not clear PWM setting

comment out this line in

```
int digitalRead(uint8_t pin)
...
// if (timer != NOT_ON_TIMER) turnOffPWM(timer);
...
```

While writing a sketch for beginners, I was doing a digital read of a PWM output
And it did not do as I expected.
What I was expecting was HIGH and LOW in about the PWM ratio
But always got LOW.

Then found this in the code
I don't see any reason to override a uses PWM setting just because their code asks for a read.
matthew

```
int digitalRead(uint8_t pin)
{
uint8_t timer = digitalPinToTimer(pin);
uint8_t bit = digitalPinToBitMask(pin);
uint8_t port = digitalPinToPort(pin);

if (port == NOT_A_PIN) return LOW;

// If the pin that support PWM output, we need to turn it off
// before getting a digital reading.
if (timer != NOT_ON_TIMER) turnOffPWM(timer);

if (*portInputRegister(port) & bit) return HIGH;
return LOW;
}
```