v3d: add flake spec@ext_framebuffer_blit@fbo-sys-sub-blit

https://gitlab.freedesktop.org/mesa/mesa/-/jobs/39905522

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22486>
(cherry picked from commit 5b376664e78d4e93c48b58e3cc3149eb222877b2)
2 files changed