turnip: Use the simplified stencil write flags for the LRZ-allowed check.

turnip: Use the simplified stencil write flags for the LRZ-allowed check.

Traces of GLES games that ANGLE has taken frequently have no-op stencil
writes, which ANGLE and Zink both pass straight through.  Given that we
support dynamic stencil state updates via tu_CmdSetStencil*(), draw time
really is the time for deciding this state unfortunately.

Reuse the fancier stencil write enables check from "can we do early z?" in
"can we do LRZ?".  This gets one set of draws in among_us to have LRZ, but
I don't see a detectable performance difference.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18691>