mesa/st: drop additional validate_ir_tree() call

This is not needed. validate_ir_tree() is called at the end of the
glsl ir linker and the IR is not modified again after so we can
drop this.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26628>

src/mesa/state_tracker/st_glsl_to_nir.cpp

@@ -523,8 +523,6 @@ st_link_glsl_to_nir(struct gl_context *ctx,
       if (shader_program->data->spirv) {
          prog->nir = _mesa_spirv_to_nir(ctx, shader_program, shader->Stage, options);
       } else {
-         validate_ir_tree(shader->ir);
-
          if (ctx->_Shader->Flags & GLSL_DUMP) {
             _mesa_log("\n");
             _mesa_log("GLSL IR for linked %s program %d:\n",