hikey960: flash-all.sh: Remove unintentionally committed skipping of userdata am: 38d4c1e6fd am: c37f55401e am: c2f3fca801

Original change: https://android-review.googlesource.com/c/device/linaro/hikey/+/1716028

Change-Id: I85d4049dd8a75b32171cb29b01e17aea0f79218c