Sorry, it can't be done.
The camera in a phone uses reflected light to produce an image, whereas scanning negatives requires transmitted light (passed through[i a negative, rather than bounced off its surface) in order to achieve the desired result.
The only way you might manage to scan a negative with [i]any] camera (whether inside a mobile phone or not) is to lay the negative on a lightbox (or light pad), then photograph it and use image-processing software to reverse the image. It's unlikely that you'd get a worthwhile result.