Multires: Enable sculpting in all subdivision levels

Return the correct sculpt level in BKE_multires_sculpt_level_get and
enable the property in the UI

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D7575

release/scripts/startup/bl_ui/properties_data_modifier.py

@@ -686,8 +686,7 @@ class DATA_PT_modifiers(ModifierButtonsPanel, Panel):
         split = layout.split()
         col = split.column()
         col.prop(md, "levels", text="Preview")
-        # TODO(sergey): Expose it again after T58473 is solved.
-        # col.prop(md, "sculpt_levels", text="Sculpt")
+        col.prop(md, "sculpt_levels", text="Sculpt")
         col.prop(md, "render_levels", text="Render")
 
         row = col.row()