Vulkan: Fix off by one when flushing staged texture updates When updating ImageHelper::flushStagedUpdates to handle base and max texture level, we got off by one when deciding if an update landed in in the range of the current vkImage. When there are 8 mipLevels and we see an update for level 8, that should not be applied, and should be preserved in updatesToKeep. Bug: angleproject:3950 Test: MipmapTest.DefineValidExtraLevelAndUseItLater/ES2_Vulkan Change-Id: I63e0c24f7885f8b0580ce212b531711aebcf0e01 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1848933 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Cody Northrop <cnorthrop@google.com>