backend: Add prefix_length to prefix smart parser
backend: Add prefix_length to prefix smart parser

Added the prefix_length field to the prefix smart parser module.

Fixes #973

garberg/NIPAP,garberg/NIPAP,bbaja42/NIPAP,SpriteLink/NIPAP,garberg/NIPAP,bbaja42/NIPAP,fredsod/NIPAP,fredsod/NIPAP,garberg/NIPAP,bbaja42/NIPAP,SpriteLink/NIPAP,SpriteLink/NIPAP,SpriteLink/NIPAP,bbaja42/NIPAP,fredsod/NIPAP,fredsod/NIPAP,fredsod/NIPAP,bbaja42/NIPAP,bbaja42/NIPAP,garberg/NIPAP,SpriteLink/NIPAP,garberg/NIPAP,SpriteLink/NIPAP,fredsod/NIPAP