i965/vs: Remove unnecessary NULL check on generate_code() result.
i965/vs: Remove unnecessary NULL check on generate_code() result.

Code generation is not allowed to fail for any reason - in fact,
fs_generator has no mechanism for failing.  The visitor is responsible
for that.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler