maximumDelay for exponential retry policy always throws an error (v8.x.x)

The code is:
```
       else if (this.maximumDelay)
                    throw new Error('Maximum delay can not be set more than 150 seconds for retry');
```

which means if any maximumDelay is set, then the error will throw

suggested fix:
```
       else if (this.maximumDelay > 150)
                    throw new Error('Maximum delay can not be set more than 150 seconds for retry');
```