i965/fs: Skip remove_duplicate_mrf_writes() during SIMD32 runs.
i965/fs: Skip remove_duplicate_mrf_writes() during SIMD32 runs.

The pass is disabled in SIMD16 dispatch mode for the same reason, it
cannot handle instructions that write multiple MRF registers at once.

Reviewed-by: Jason Ekstrand <68c46a606457643eab92053c1c05574abb26f861@jlekstrand.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler