Remove layout_sections_again argument to size_stubs

Remove layout_sections_again argument to size_stubs

This was originally the first place that a function in
bfd/elfnn-aarch64.c was given a reference to
gldaarch64_layout_sections_again, and hence was the natural place to
store the function onto the elf hash table.

Ever since the introduction of elfNN_c64_resize_sections we have been
performing this operation in that function before this size_stubs
function.

Hence it seems sensible to remove the argument and now superfluous
operation from elfNN_aarch64_size_stubs.