To make sure TextureVk::syncState is called before generateMipmap.

Bug: angleproject:4551
Change-Id: Ibce0738b72fc81270e07617f04ffee57f1c8ed20
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2248209
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>