freedreno: Fix the cpu-prep wait to be "infinite".

We don't need to restrict our timeout to 5 seconds, because the kernel's hangcheck will ensure that the wait completes in finite time if the GPU gets wedged. If the GPU is making progress, we don't want to time out early and have pipe_transfer_map() return an error, causing glReadPixels() to throw a confusing GL_OOM even though we're not out memory.

The INFINITE arg to this function isn't actually infinite, it's limited to an hour. But an hour of GPU processing to wait on is probably plenty.

This 5s timeout has caused problems with the CTS on freedreno at high parallelism, and I suspect is the cause of recent issues in the closed traces replay jobs.

@tomeu hope this helps