Download Huawei P9 Lite VNS-L22C185B130 and VNS-L22C185B140 official update firmware from this post and follow instructions after the download options to learn how to flash.
This stock rom is specifically meant for VNS-L22C185 variants. Flashing on a different variant might cause a brick, if flashing is at all successful.
Download Options
File Name: update.zip (VNS-L22C185B130)
Size: 1.58 GB
Android version: 6.0
Firmware – Download
File Name: update.zip (VNS-L22C185B140)
Size: 1.62 GB
Android version: 6.0
Firmware – Download
How to flash
Once you have downloaded the firmware from above link, click here to learn how to flash.