nir: Make lower_wpos_ytransform_block a void function.
nir: Make lower_wpos_ytransform_block a void function.

The return value was used for the old nir_foreach_block callback system,
but at this point it no longer means anything.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Rob Clark <915c10c999604870200b6defbe633d857c856ca0@gmail.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler