GPencil: Fix showing wrong material in brush panel with pinning

The options of the material are from object material not pinned material.

If the brush is pinned, the material must be the brush material and not the object material.

release/scripts/startup/bl_ui/space_view3d_toolbar.py

@@ -1781,7 +1781,7 @@ class VIEW3D_PT_tools_grease_pencil_brush_option(View3DPanel, Panel):
             col.prop(gp_settings, "angle_factor", text="Factor", slider=True)
 
             ob = context.object
-            if ob:
+            if ob and brush.gpencil_settings.use_material_pin is False:
                 ma = ob.active_material
             elif brush.gpencil_settings.material:
                 ma = brush.gpencil_settings.material