dm: linker_lists: Add a way to declare multiple objects

dm: linker_lists: Add a way to declare multiple objects

The existing ll_entry_declare() permits a single element of the list to
be added to a linker list. Sometimes we want to add several objects at
once. To avoid lots of messy declarations, add a macro to support this.

Signed-off-by: Simon Glass <sjg@chromium.org>