Vulkan: Remove emulated clears before mipmap generation If the image is recreated for mipmap generation, and if the format used is emulated, clears are automatically staged for all levels of the image. Since non-base levels will be completely rendered to (using blit, so not through the staging buffer), there is no point in performing these clears for non-base levels. This change drops those clears. Note that another change will drop the clear for base level if detecting that a future update will supersede it, for example because the base level is being copied from the old image. Bug: angleproject:4551 Change-Id: If2f10cf67e24b44243b29d22bfcf1cb933895cd7 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2262575 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>