Vulkan: clean up framebuffer clear The Qualcomm bug workaround is changed such that clears still go through the render pass loadOp, but the render pass is immediately closed. This allows us to remove a few fallback methods. Bug: angleproject:2361 Change-Id: I24c3884a183f8bb40673e922773f70faffad848f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1545524 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>