v3dv: actually enable early Z

We had done all the plumbing for this but EZ can be disabled in 3 places
and we were never setting the enable bit in the configuration bits packet.

Also, configuration bits must not enable EZ if this has been disabled in
the RCL for the whole frame, which we do if we don't have a depth
attachment at all.

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