Vulkan: Updates to perf counters 1. don't reset pipeline cache hit / miss counters after every frame 2. bugfix in LinkTaskVk::getResult(...) 3. accumulate counters in WarmUpTaskCommon::getResultImpl(...) Bug: angleproject:8297 Change-Id: I39d7e1a438d78e2e353c5cf8246fb24fb3cfefea Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5529942 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: mohan maiya <m.maiya@samsung.com>