st/nir: Drop unused gl_program parameter in VS input handling helper.

Nobody uses this, so let's drop it.  This makes the helper callable
from places without a gl_program.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/mesa/state_tracker/st_glsl_to_nir.cpp

@@ -81,7 +81,7 @@ st_nir_fixup_varying_slots(struct st_context *st, struct exec_list *var_list)
  * on varying-slot w/ the VS outputs)
  */
 static void
-st_nir_assign_vs_in_locations(struct gl_program *prog, nir_shader *nir)
+st_nir_assign_vs_in_locations(nir_shader *nir)
 {
    nir->num_inputs = 0;
    nir_foreach_variable_safe(var, &nir->inputs) {
@@ -810,7 +810,7 @@ st_finalize_nir(struct st_context *st, struct gl_program *prog,
 
    if (nir->info.stage == MESA_SHADER_VERTEX) {
       /* Needs special handling so drvloc matches the vbo state: */
-      st_nir_assign_vs_in_locations(prog, nir);
+      st_nir_assign_vs_in_locations(nir);
       /* Re-lower global vars, to deal with any dead VS inputs. */
       NIR_PASS_V(nir, nir_lower_global_vars_to_local);