nv50: fix streamout queries

Prior to an earlier commit, xfb queries were not being marked as 64-bit. The end result of this is that they would never appear to be "ready", which in turn led to there always being a wait happening.

Once these got marked as 64-bit, we started checking the attached fence for being signalled. However the screen fence does not seem to be enough to wait for the streamout query data to actually be written out. So instead we add a bit of extra "data" which emulates the 32-bit query way of doing things (with the payload in front) which is emitted from the same "unit" as the other streamout data. This seems to be sufficient.

Note that it does not seem to be required to actually emit the final 32-bit query from the streamout unit, but that seems logical and perhaps there are edge cases where it is required.

While at it, also make the sequence management/initialization more similar to the nvc0 driver.

Fixes dEQP-GLES3.functional.transform_feedback.*

Fixes: 58d47ca3 ("nv50: add compute invocations counter") Signed-off-by: Ilia Mirkin imirkin@alum.mit.edu