Cleanup: Eevee/Workbench: Remove non-needed matrix inversion

Theses are garanteed by the depsgraph now.

source/blender/draw/engines/eevee/eevee_volumes.c

@@ -503,9 +503,6 @@ void EEVEE_volumes_cache_object_add(EEVEE_ViewLayerData *sldata,
   DRWShadingGroup *grp = DRW_shgroup_material_empty_tri_batch_create(
       mat, vedata->psl->volumetric_objects_ps, sldata->common_data.vol_tex_size[2]);
 
-  /* Making sure it's updated. */
-  invert_m4_m4(ob->imat, ob->obmat);
-
   BKE_mesh_texspace_get_reference((struct Mesh *)ob->data, NULL, &texcoloc, NULL, &texcosize);
 
   float(*imat)[4] = ob->imat;

source/blender/draw/engines/workbench/workbench_deferred.c

@@ -1072,7 +1072,6 @@ void workbench_deferred_solid_cache_populate(WORKBENCH_Data *vedata, Object *ob)
 
           if (studiolight_object_cast_visible_shadow(wpd, ob, engine_object_data)) {
 
-            invert_m4_m4(ob->imat, ob->obmat);
             mul_v3_mat3_m4v3(
                 engine_object_data->shadow_dir, ob->imat, e_data.display.light_direction);