glsl: use only copy_propagation_elements

Now that the elements version handles both cases, remove the
non-elements version.

Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Thomas Helland <thomashelland90@gmail.com>

src/compiler/glsl/glsl_parser_extras.cpp

@@ -2214,7 +2214,6 @@ do_common_optimization(exec_list *ir, bool linked,
    OPT(do_if_simplification, ir);
    OPT(opt_flatten_nested_if_blocks, ir);
    OPT(opt_conditional_discard, ir);
-   OPT(do_copy_propagation, ir);
    OPT(do_copy_propagation_elements, ir);
 
    if (options->OptimizeForAOS && !linked)