r600: increase possible stack size in binary code
With the trace posted in #6969 (closed) we get a nesting level of 149, so make it a round 256 of stack entries.
Related: #6969 (closed)
Fixes: a4840e15 r600: Use nir-to-tgsi instead of TGSI when the NIR debug opt is disabled.
Edited by Gert Wollny