jfs: Simplify code

Calling 'list_splice' followed by 'INIT_LIST_HEAD' is equivalent to
'list_splice_init'.

This has been spotted with the following coccinelle script:
/////
@@
expression y,z;
@@

-   list_splice(y,z);
-   INIT_LIST_HEAD(y);
+   list_splice_init(y,z);

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>