ocfs2: remove mostly unused field from insert structure

ocfs2_insert_type->ins_free_records was only used in one place, and was set
incorrectly in most places. We can free up some memory and lose some code by
removing this.

* Small warning fixup contributed by Andrew Mortom <akpm@linux-foundation.org>

Signed-off-by: Tao Mao <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>