ocfs2_grow_branch() not really using it other than to pass it to the
subfunctions ocfs2_shift_tree_depth(), ocfs2_find_branch_target(), and
ocfs2_add_branch().  The first two weren't it either, so they drop the
argument.  ocfs2_add_branch() only passed it to
ocfs2_adjust_rightmost_branch(), which drops the inode argument and uses
the ocfs2_extent_tree as well.

ocfs2_append_rec_to_path() can be take an ocfs2_extent_tree instead of
the inode.  The function ocfs2_adjust_rightmost_records() goes along for
the ride.
Signed-off-by: Joel Becker <joel.becker@oracle.com>