glsl: Remove duplicate definition of gl_MaxTess*ImageUniforms built-in constants.

These seem to have been re-added at some point during the
ARB_tessellation_shader implementation work.  AFAICT the second
(correct) definition of each constant would have had no effect because
the symbols were already defined.

Reviewed-by: Tapani Pälli <tapani.palli@intel.com>

src/glsl/builtin_variables.cpp

@@ -754,8 +754,6 @@ builtin_variable_generator::generate_constants()
                 state->Const.MaxImageSamples);
       add_const("gl_MaxVertexImageUniforms",
                 state->Const.MaxVertexImageUniforms);
-      add_const("gl_MaxTessControlImageUniforms", 0);
-      add_const("gl_MaxTessEvaluationImageUniforms", 0);
       add_const("gl_MaxGeometryImageUniforms",
                 state->Const.MaxGeometryImageUniforms);
       add_const("gl_MaxFragmentImageUniforms",