v3dv: make the driver more robust against OOM

This is generally very difficult to handle properly everywhere, but
at least this is good enough to make the few CTS tests for this happy.

Fixes (on Rpi4):
dEQP-VK.wsi.xlib.swapchain.simulate_oom.*

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>
6 files changed